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Looks really nice, thank you for open-sourcing. I keep a directory of opensource alternatives. Would you say this is a Discord or Slack alternative?
> You’re probably familiar with the one that rhymes with “knack”, or the one that rhymes with “beams”, or the one that rhymes with “this gourd”.

> Chatto is just like those.

from TFA. Seems yes.

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I've been testing/using chatto since early on and I'd say it's both and neither. It feels much nicer to use than Slack, but as of now it's missing some of the more "Enterprise" features. I would probably say it's a Slack-like Discord? But from the architecture it would be capable of playing as a full Slack replacement.

I also maintain a Chatto bot framework and a Tauri client, need to update those now :)

What makes it nicer to use than Slack?
For me, primarily the performance tbh. Chatto just flies and Slack feels incredibly sluggish. And from the "vibes" it just feels better designed, I like the overall user experience, it feels technologically solid but also looks nice and works how I feel it should. Hard to put my finger on it exactly.
In terms of inspiration and also the market that I want to go after with Chatto Cloud, this is definitely aiming to be an alternative to Slack, Teams, Mattermost et al. I've tried to make it friendly and casual enough to _also_ work as a Discord alternative, though.
I've been trying to find a Slack replacement since Salesfarce started ruining it and I must have tried out maybe 50 potential replacements, paid and free. This is the first self-hostable, open source one I've seen that doesn't look like design is the very last item on an amorphous future roadmap. In fact, there's some really nice design and UX touches in Chatto. Congrats on the launch, I'm absolutely certain we'll move off Slack to this when the dedicated apps arrive, maybe even before.
Amazing. And with SSO out of the box without weird "Oh, SSO is Enterprise only" BS.
Ah mobile app is not ready yet. I am looking for some alternative to matrix because running it with bots is a bit convoluted, i.e. you have to have limit of edits of message for model streaming or you will kill entire room. Or I never seen robots in matrix sending encrypted messages. Why bother than? Anyway if mobile will be a thing this seems like perfect thing to have for your family and friends.
I created a Tauri based app but IMO it's not ready for prime time on mobile. On desktop, it's my daily driver for Chatto. If anybody wants to contribute, the foundation (desktop & mobile) is at https://github.com/teal-bauer/chatto-tauri
Interesting but could you put few screenshots there? Of both desktop and mobile? It is really hard to invest time into installing something that you cant see anywhere prior, and it will be really easy to do for someone that is using it daily. Sorry for complaining. Seems like nice project.
For now it's just a Tauri wrapper, so it looks more or less like the mobile web / PWA except it might be easier to handle notifications and share intents etc. compared to a pure PWA play. Now that the API is settled, it might make sense to go pure native.

The Tauri wrapper was originally just for desktop convenience and the Android target was more of a proof of concept initially.

Sure I understand though, I have honestly no idea what tauri is really. Sure there is a link and it looks like some kind of web framework. Looks nice but it is hard to picture how chat application written with that would look like. I am not trying to force you to do want I want. I just think it is in a good taste to put some screenshots or even a gif. But I understand your reluctance.
Tauri is like a nicer Electron, instead of shipping a full Chrome with the app it uses the platform's browser libraries. So the app looks almost exactly like the mobile web version, which looks like the desktop version that you can see in the screenshots on Chatto.run
Yeah its unfortunate there's an AI app on the apple store with the same name
I’ve known Hendrik for years, and he is one of the most talented developers I’ve ever met. I’m confident this project will become successful very quickly. Beyond the project itself, what fascinates me most is how he single-handedly developed it by leveraging agentic coding.
But I read here every day that agents can't code. And that "real developers" spend more time fixing AI bugs than producing code, and it slows them down.

You mean to tell me smart people can leverage these tools to do things at a scale they couldn't before? Blasphemy!

Are you sure you read that here? I came back yesterday after a hiatus and I’ve been dismayed how many posts are just “yeah, I just run Claude all day” without a hint of embarrassment or shame.
I agree with this sentiment so much but before I could figure I turned into it. I'm feeling torn - it's helping me write and ship good code as I couldn't before, but it feels like I don't understand the real price of using it non-stop.
I run Claude all day, and produced some good shit, but I'll admit to being thoroughly embarrassed that I haven't looked at it all, won't make it public, won't put my name on it, won't pick a license. I'm depressed about the whole thing and might take it up with a therapist.

My eyes are still rolling from GP's comment:

> he single-handedly developed it by leveraging agentic coding

>he single-handedly developed it by leveraging agentic coding

so, unmaintained in a year because the sole developer got bored/didn't make money from it/burned out ?

Great, I'll run my entire company on it!

are you ok? what do you need constant updates for on a self hosted chat server/client? it already looks like it has most of the features
"why would you need features on the thing on which the vast majority of your company's interactions and unofficial note keeping and knowledge building is happening" is a fun question to ask, when the project in question doesn't have bot actions or webhooks.
just implement them yourself if you need that, takes a few tokens
Yes. Every day. Look at the replies for crying out loud. Including yours.

Why should anyone be embarrassed? You should be embarrassed that you think you are morally superior for not using Claude. Let me guess, you don't own a tv either? So cool.

Claude is regularly finding bugs and security issues people like you slop coded into widely used tools.

don't forget "where are all these beautiful apps that supposedly everybody vibe codes now?"
Who says this? "Beautiful" vibecoded apps are a dime a dozen. Getting support or continued feature development for those beautiful apps after the developer's AIDHD moves on to their next half-baked idea is usually the differentiator between a good vibecoded app and a bad one.
> But I read here every day that agents can't code. And that "real developers" spend more time fixing AI bugs than producing code, and it slows them down.

This is all correct, though. I haven't tried this, but I can guarantee it's a buggy, incoherent mess, same as every other vibe coded app I've ever tried, no exceptions.

Yeah, the crap I vibe coded is buggy as hell too. It takes a lot of tokens and time to polish my agentic turds.
These kind of comments just spike the conversation and leave no room for nuanced opinions or discussion.

A lot of garbage is also being produced and a lot of people have to clean it up, right? Hopefully that’s not too controversial of statement?

> These kind of comments just spike the conversation and leave no room for nuanced opinions or discussion.

It's a 20-something day old account.

It took him a year to build. So yeah, obviously if someone spends a year working on something with an LLM they can produce a good product.

The slop we're seeing from people using AI is because they pump it out in a month or two and then call it a day.

The big question is: how do we tell the difference?

If 99.9% of LLM-smelling projects is vibecoded garbage, why should anyone assume that your LLM-smelling project is the 0.1%? If I spend all day digging through dogshit to find the one diamond, I'll just end up going home empty-handed smelling of dogshit.

AI tells are a giant red flag indicating to potential users not to waste time on it. Want people to take your new pet project seriously? Don't use AI! And yes, that does include even the genius 100x engineers who can use LLMs responsibly.

Alright, I was vaguely interested for a little, but you convinced me to avoid it.
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Well that’s just snarky and not very nice. The guy has 30 years experience as a dev according to a sibling comment so it’s not as though it’s some vibe coded junk. Why do you believe a good dev can’t use AI to assist in writing great code?
I'm not interested supporting in anyone who is willing to build on stolen property just so that we can accelerate enshittification and damage the environment. When the AI companies pay artists for their training material, stop building gas pipelines directly to data centers, and work on putting UBI in place before they try to replace all white collar labour, it may be worth revisiting.

There's a reason that believing AI is bringing a better world is a more fringe position than believing in telekinesis. The AI companies are strip-mining the commons, and leaving the world worse off for it.

Good luck! The world needs more rms types (specifically referring to people who adhere strongly to moral principles over expedience)
Are you sure about "rms types" specifically? Stallman is very ineffective in his proselytization, owing to his complete refusal of any kind of compromise or concession to dissenting positions. This stance may keep your soul pure and righteous, but it won't bring you one millimeter closer to your objectives.
Yes, I am. I think Chatto looks great, and I use AI in my job every single day. I've been following OpenAI since MuseNet. I'm uncomfortable about the coming Kuznets curve for AI, the wealth concentrating effects, the energy use, the stunting effects on human intelligence and connection, and the abuse of training data associated with AI. I am that "let's take a nuanced approach and find out how we can get most of the good without most of the bad" person. I think people like me are probably the majority stance when it comes to AI use among tech people. I also think that we'll be steamrolled by moneyed interests and society-level incentives in the short term, and I don't really see a way around that.

In the absence of a way to win with nuance, I think it's just nice to have people who live rigidly by their principles as an example of what is possible.

Would you say copying and finding solutions on Stackoverflow is building on stolen property?

I'm no fan of AI companies, but I fail to see how people using it to build open-source software is a bad thing.

Are the solutions on stackoverflow licensed in a way that allows people to use them that way? Is this true for AI training data?
Depends on whether the answer o. Stackoverflow was given willingly or at gunpoint ^^
How do you feel about open weight models, and fully open source models (all data, training scripts/recipies, and model weights all open source)?
I'm not aware of any models with full training data available, let alone available with full licensing.

The process of training and using them is also not likely to be any better than commercial models. 23% of Ireland's power is going to data centers, spreading that among less efficient hardware in less efficient setups is unlikely to be better, unless the models are so bad nobody uses them.

And I'm also not aware of anyone working on these models trying to reduce the social damage they are going to do.

>I'm not aware of any models with full training data available, let alone available with full licensing.

Check out the OLMo family from the Allen Institute for AI: https://allenai.org/blog/olmo3

Also worth looking at EleutherAI, LLM360, SmolLM, Apertus. Apterus even respects opt-out notices in their collection of the dataset they distribute. KL3M from Kelvin Legal is even trained on a 100% copyright-free legal/governmental corpus.

>23% of Ireland's power is going to data centers

This isn't even a rounding error in terms of global energy usage. Besides, renewable energy is cheaper than non-renewable energy now. Energy demand itself directly drives the deployment of renewable energy. Needing more electricity in a capitalist country literally causes the energy mix to become more green over time.

>And I'm also not aware of anyone working on these models trying to reduce the social damage they are going to do.

Is it fair to account for the social damage without accounting for the social good, like the unprecedented democratization not just of mere information, but knowledge and understanding itself, around the world? Think about how many deaths will be avoided, how many billions or trillions of years of human life will be gained over time, all of the people that gain access to a personalized, individually tailored tutor for any subject on earth, all of the medical and legal advances, etc.

You're right, the usage in the USA is bigger.

https://www.eia.gov/todayinenergy/detail.php?id=67704

Across all cases, servers alone accounted for an estimated 7% of commercial sector electricity consumption in 2025. Data center server electricity use grows to 22%–33% of commercial building electricity use by 2050 across our cases.

Distributing that outside of special purpose, optimized data centers isn't going to bring that number down.

> Apterus even respects opt-out notices in their collection of the dataset they distribute.

Yeah. Uh. That's the bare minimum.

> Check out the OLMo family from the Allen Institute for AI: https://allenai.org/blog/olmo3

Is this a joke of just blatant publicity for this Billionaire "philanthropist"? This olmo uses random data of totally infringing license database such a StackEdu (https://huggingface.co/datasets/HuggingFaceTB/stack-edu).

I took this first dataset from what olmo claim to use and check a random used data -> https://github.com/rodriguescarina/URI . Boom MIT licensed (where is the credit?), 0 opt-in for AI training as far as I see.

> Needing more electricity in a capitalist country literally causes the energy mix to become more green over time.

Perhaps true, but meaningless except as a vanity metric if fossil fuel usage rises as well.

EU and US have had declining total carbon emissions for over 2 decades now. The global rise in total carbon emissions comes from outside the west.
> trying to reduce the social damage they are going to do.

I'm worried about that in particular because when I started using AI I often felt I wanted to say something nice to it, like just "thanks" after I got someting working with its help. But then I started thinking I'm crazy, that's a waste of typing, what does it matter if I tell AI "thanks" or not.

So I don't thank AI any more, do you?

But that means we get used to this style of conversation and soon enough we don't tell humans thanks either. We dont' put in the energy to lubricate our social interactions. I'm worried that interacting with AI will make us all rude.

> anyone who is willing to build on stolen property just so that we can accelerate enshittification and damage the environment

Others have made solid arguments(Stackoverflow, open weight models, and fully open source models) - but I encourage you to study the ecosystem post War II and the 1970's Silicon Valley, especially how the semiconductor companies "innovated".

The tiny little MOSFETs you're employing to read this are all built on stolen IP.

As someone famous said, good artists copy; great artists steal.

> The tiny little MOSFETs you're employing to read this are all built on stolen IP.

The alternative to an LLM typing code is a human typing the code. What is the alternative to microchips?

> As someone famous said, good artists copy; great artists steal.

And people who could not be further from artists, or even art enjoyers, think stealing makes them artists, too. Because they're that far removed from art, or any grace, really.

Which doesn't go against OP or the project, which I find delightful. Although I generally share many reservations of "AI critics", I'm also a starved: if it's snappier and uses less resources than something humans coded, come right in! At least if it's a neat thing like this seems to be, and not some sprawling trojan horse with code that "works" but looks terrible... machine optimized stuff that is opaque to and not made for humans need not apply.

I'd bet 99% of overall token usage has nothing lasting to show for it, and of the 1% that actually compound into anything 99% are nothing like this. So just like a broken clock can be right twice a day, a super correct soldier of Butler can hold fire twice a day, no?

vacuum tubes : MOSFETS :: human coders : LLMs
> What is the alternative to microchips?

There are different ways to answer this. One person gave a literal answer - Vacuum Tubes. My, alternate answer is, humans. Computers are machines that automate human processes. If we didn't have a digital domain, we would just be doing what we were doing before it, printing and writing.

> I'd bet 99% of overall token usage has nothing lasting to show for it, and of the 1% that actually compound into anything 99% are nothing like this

What you're betting with?

LLMs have changed to game on velocity of knowledge work. The future has changed and "nothing lasting to show for it" is a very limited take on the matter.

LLMs have democratized knowledge.

"The future has changed", oh my.

The idea that "the future is changed now, so you can't change it again" is the language of abuse, not the language of wisdom. We'll just change it again by draconically punishing thieves. Then we can have the best of both worlds: cool tech, and no Eloi/Morlock bs.

Anyway, I simply meant that most vibe coded stuff doesn't seem to get maintained, and that most token usage doesn't produce any artifacts to begin with.

> "the future is changed now, so you can't change it again"

that's not what I said.

As technologists, we repeatedly change the future - that's what makes all the pain, sweat and tears worth it. 35 years ago, when I was getting serious about computers, buying them and encouraging others to use them, people would shake their fingers at me, saying how these bulky TVs that you can press buttons at were a passing fad, that it was an absolute waste of everyone's time even thinking one would sit in front of a TV and press at buttons for more than an hour a day, that there was no reasonable way it would translate into anything but extremely niche entertainment. They would lecture me on how I was a kid who didn't know any better, that I was wasting my time out of ignorance and that I should continue studying organic chemistry and become a doctor because who didn't need a doctor?

> most vibe coded stuff doesn't seem to get maintained

even if this was true, cost of code consumption and generation has fallen so much, that anyone in a developed country can point their favorite agent to the "unmaintained vibe coded stuff" and then maintain it to their liking or rewrite it from scratch the way they wanted it to.

> most token usage doesn't produce any artifacts to begin with

Your previous statement contradicts "doesn't produce any artifacts" directly. Given what you have told me, the shallowest, congruent argument that can be made is "most token usage produces unmaintained vibe coded stuff".

It looks like you don't necessarily like what LLMs are providing to society and I can see why one would like to hold that opinion. I don't agree with that at all, because it's literally untrue given the insane demand - both from an everyday Joe and from corps the world over.

The most I can do is encourage you to set aside your current stance, and just for one day, consider what if you could use LLMs to improve your life. What would you do?

> even if this was true, cost of code consumption and generation has fallen so much, that anyone in a developed country can point their favorite agent to the "unmaintained vibe coded stuff" and then maintain it to their liking or rewrite it from scratch the way they wanted it to.

Yes, and? In context, my point was that as far as vibe coded stuff (that I saw so far, and that gets posted on HN), this is head and shoulders above the usual goes. This general evangelism of LLM that isn't even aware of the context is really grating.

> It looks like you don't necessarily like what LLMs are providing to society

I hate what they took. If you steal from Meta, they sue you. That is all there is to say.

> The most I can do is encourage you to set aside your current stance, and just for one day, consider what if you could use LLMs to improve your life. What would you do?

Do you not understand that ethics can be a value in and of itself? I'm not ethical to interact with trinkets, I interact with trinkets (with gimmicks, with toys, with product, with dust) to be ethical. The best you can have you were born with: integrity. How much of that we can preserve is the only challenge in life I take seriously. You're asking someone who dines like a king every second what they would cook if they were "allowed" shit as an ingredient.

I have no "qualms" toying with LLM. I did, I got bored, so now I don't. When it comes to generating "art", I actually do refrain from using it even when it could be useful, because yes, it's generally theft. Wake me up when there are LLM fully trained on licensed content, and in the meantime, accept a no.

So we are at a stage where AGPL 3.0 is not enough and using AI assisted coding is considered evil?
your comment sounds like your the type to say you won't buy a house in North America cause its stolen land...
Ah, another person who thinks that as long as they benefit in the short term, who cares about the damage done? Who knows, maybe you'll end up making enough money to avoid any future consequences, too. Good luck with that.
You're convincing me to side with this ori_b here.

I knee-jerked downvoted their initial take because it reads as ineffective. boycotts just concentrate the energy of the other side even more. If anything we need more participation across the spectrum to shape what isn't going away.

But reading the discussion, deliberate advocacy and taking a stance counts too. Um yeah, there is a problem with profiting from real-estate-go-up willful-ignorance.

Glad to see people trying to talk sense in this community but the AI chill here is very strong. Reminds me of the proud "we should go back to our military-industrial root".

Also funny how it's always about "the smartest guy I ever met" impliyng other dev aren't that smart. There are easily tens of thousands of devs who are way above anyone's here level but there are coding OS module, GNU tooling or other less shining stuff, or there are not American enough.

It's tiring to see the usual corp slop : github, twitter or blue sky, vibe coding, etc. Then see the complain years latter than the product was "enshitified", all was there from the beginning. Think about the real FOSS software (GNU tooling, ffmpeg, Godot, codeberg/forgejo) to see long term software than work and carry all this money-makimg mess.

Ass for the chatto the dependency mountain is a red flag to me, this is asking for problem in my opinion, were talking primarily about sending text here.

Stealing ideas, intellectual property (IP), etc are happening throughout the age of the human civilization, that does not prevent us as human moving forward.

That's why there's little to no credit given to Muslim scholars (Arabic, Persian, Moorish Spain, etc) by the western scholars, by conveniently dismissing the Muslim golden era as "Dark Ages" but at the same time stealing the knowledge (idea, equations design, tools, etc) for most of the prior inventions by the Muslim scholars, for example the telescope.

Even worse not only the knowledge (ideas, design, equations, tools, etc) in science, engineering and technology were blatantly copied and stolen, no credit is properly given to these Muslim scholars contributions by saying that the Muslim scholars at best were just translating the Greeks works and ideas [1]. I suspect that Newton also blatantly copied the many great works by al-Haitham (Alhazen) but not giving him proper credits [2].

C'est la vie, and life goes on.

[1] Islamic Astronomy and Copernicus:

https://www.tuba.gov.tr/files/yayinlar/bilim-ve-dusun/TUBA-9...

[2] Ibn al-Haytham (Alhazen):

https://en.wikipedia.org/wiki/Ibn_al-Haytham

Firstly, there is a difference between a telescope and the prior advances that led to a telescope being invented. The telescope was not invented by a muslim scholar, hence that being why no one gives credit to one of them for that.

Secondly, to this claim:

> That's why there's little to no credit given to Muslim scholars (Arabic, Persian, Moorish Spain, etc) by the western scholars, by conveniently dismissing the Muslim golden era as "Dark Ages" but at the same time stealing the knowledge (idea, equations design, tools, etc) for most of the prior inventions by the Muslim scholars, for example the telescope.

From the link you provided, in the very first paragraph:

> The works of Alhazen were frequently cited during the Scientific Revolution by Galileo Galilei, René Descartes, Johannes Kepler, and Christiaan Huygens.

No credit or frequent credit - which is it?

>No credit or frequent credit - which is it?

>>there's little to no credit given to Muslim scholars

Again, in the link you provided, in the very first paragraph, it mentions several great names who are said to have given frequent credit to muslim scholars. Are you saying that is false? If so, you have the ability to edit that Wikipedia article, and you should.

Don't forget the legacy section, where there is a long list of people and organisations giving him enormous credit.

https://en.wikipedia.org/wiki/Ibn_al-Haytham#Legacy

The fact that Newton did not cite Alhazen or Al-Haytham in his seminal and infamous optic books in English tell you what you need to know regarding the treatment by the western scholars of the muslims scholars [1],[2].

IMHO, this critical omission caused most of the modern optical books and textbooks did not include Alhazen or Al-Haytham eventhough he literally contributed to modern optics more than Newton himself. I was educated in my high school in England, and in my Physics class no muslim scholars name ever mentioned in my many textbooks and in classes. The same goes to my chemistry and math classes.

Most probably the word camera (from the Arabic word kamar meaning room) was derived from his experimental work on optic.

Mind you this little to no credits happened across the board from , math, physics, chemistry, biology, astronomy, medicine, etc.

To put the things in perpective Now if you don't cite seminal prior work related to your research your thesis will be subjected to re-submission.

Imagine if Einstein did not even mentioned Newton's contributions in gravity, the English people will be go to war with Germany OK, they did but that's for totally different reasons.

[1] Did Isaac Newton plagiarize his work from Ibn-Al Haytham?

https://www.quora.com/Did-Isaac-Newton-plagiarize-his-work-f...

[2] Opticks:

https://en.wikipedia.org/wiki/Opticks

You tell me he has 30 years of experience, then you tell me that he developed the chat app in a way that negates those 30 years of experience.

Like, either the 30 years matter or they don't. If you're using agentic coding, while copying the two most popular chat applications (Discord and Matrix/Element), you'll need 5 years of development experience at most.

The big thing about AI is that it lets you explore a new domain outside your expertise almost effortlessly.

Yep, instantly lost all interest. I'm not sure how impressive it is that somebody vibecoded a browser-based chat app over the course of several months. I also don't know what difference it makes that the dev is a really cool guy, or whatever; I'm sure he is, but the usage of AI is unethical, plain and simple, and I won't support it at all whenever feasible.
I second that. I've personally known him for almost 30 years by now, and he's still one of the smartest, most experienced, and most curious devs I've ever met. All around good guy, would work with him again any day of the week.
Has he made anything else interesting?
20 or so years ago him and czottmann wrote a nice little wiki software that I used, WakkaWiki. Following him/them and their work ever since. Crazy.
How is that fascinating? That's what makes up most of the tedious Show HN posts these days.
There is a difference between vibe coding (asking an agent to generate an app from specifications) and leveraging agents to go faster on your vision. You can still decide to control the technical architecture and decisions and just let agents type on your behalf.
The anxious pendulum swings hard between "show me something real that is well done" and "what is interesting about it, that's what everyone does".
> It’s designed to be extremely easy to self-host on your own infrastructure.

Kudos for this. Per the docs: https://docs.chatto.run/,

> Chatto ships in a compact, self-contained binary

> it uses NATS, a compact message broker that also ships with a built-in stream persistence engine [...] NATS is just as easy to provision as Chatto, and most of our examples will show you how.

> you can also configure an external S3-compatible object storage for Chatto to store your files in, and we strongly recommend doing

> The actual calls are powered by LiveKit (Apache-2.0), which you need to deploy alongside Chatto. As with NATS, the deployment examples show the required wiring.

> ...

And kudos for backing it up with real guidance. Great project.

Can it be installed on Cloudflare or Vercel or something else that is easy/cheap/free?
This is super cool. More options is always good. Something that is confusing about the docs though... is there a desktop application? The screenshot implies there is but I couldn't find the docs to download THAT.
It's a first-class PWA currently but no native desktop apps.
Sounds like something I could finally build with Kotlin Multiplatform...
There is a Tauri wrapper that I built early on because I wanted the desktop convenience (autostart, separate app, etc) that Firefox+PWA couldn't offer, I use the desktop version as my daily Chatto driver. The mobile build is more of a proof of concept for now. Check it out: https://github.com/teal-bauer/chatto-tauri
Hi, I'm making Chatto!

Chatto so far fully commits to providing a great PWA experience. The screenshot you're seeing is of the PWA.

I'm aware that a lot of people want desktop and mobile apps. These will be coming at some point, at least as wrappers around the PWA.

It's a really cool project and clearly you put a lot of effort behind it. I like that it's self-hosted and may try it out on my homelab. Thanks for making it!
Wow, it's using NATS! I used NATS extensively 10+ years ago, and I'm happy to hear it's still around. Our infrastructure had hiccups across our fleet of machines, but one part that always remained up and running without complaining on some dinky machine was NATS. Well, that and Redis. No complaints ever.
We are building something B2B expected to have good enough scale ... we had to choose between kafka, nats, redpanda and rabbitMQ .... We went ahead with NATS .... don't know why, but, when we went through all the docs, including setup and operational, NATS just felt right.
We are in the same decision making stage and trying to choose between rabitMQ, Kafka, NATS and some solutions built on top of Redis.

Did NATS eventually worked well?

Excellent. We already tested at okayish scale of 5 million messages per minute, with each message being less than 1KiB. Do note that NATS can easily handle 100x this scale. It's just what we had tested during initial days.
Wow!

I have a stupid question - as I understand NATS works very well as a “message” pipe/bus. Anyway to get Redis type cache functionality as well ? Is it something possible ?

JetStream (not NATS) has a built-in key/value store. Relevant thread (old, from 2023): https://github.com/nats-io/nats.go/discussions/1507

someone did some benchmarks in 2025:

    nats bench kv put --size="128" --msgs 1000000 --storage file
    1m3s → Pub stats: 15,656 msgs/sec ~ 1.91 MB/sec
    
    nats bench kv get --size="128" --msgs 1000000
    59s → Sub stats: 16,720 msgs/sec ~ 2.04 MB/sec
I have personally not used this though.
Thank you! Jetstream looks useful. For a platform which is production our Redis costs are getting prohibitively high. I was on the look for alternatives and perhaps in the software reliability tool [0] I am buildin try out Jetstream.

[0] https://github.com/bobinson/vulture

I’d also recommend looking at Swytch (docs.getswytch.com, particularly the economics page).

Disclosure: I’m a founder.

Hi, Chatto developer here.

NATS and its built-in Jetstream stream persistence engine are a miracle. I love them both so much. And if your app is itself written in Go, you can just embed them for simple deployment scenarios (like Chatto does.)

Inspired by Chatto, I also built some prototypes on the NATS (+Go) stack and it's been a dream. Feels like a severely under-hyped technology :D
looks like a great project, want to get AI bots talking to each other
Would English speakers pronounce this as "Chat-to"? To a Japanese person, this clearly sounds like "Cha-tto," which simply means "chat."
as an english speaker, i would pronounce it "chat-oh", but i'm open to correction
I don't know what the "official" pronunciation is, but I would say "Chat-o" is probably right.
At least here in colloquial "rolo" spanish people use to call "chato" (which would sound the same as "chatto") someone with a pug, snub nose
Linguist here. It would likely be pronounced with a flap/tap, i.e., it would rhyme with shadow
Let Chatto cast a shadow on your private communications!

The marketing practically writes itself.

> And you can just self-host it. For free, too! (A weird thing to write, but the OSS chat app space has become very weird in many ways!)

Wait, what? There are open-source chat apps that you have to pay to host yourself? How does that work? Or did I misunderstand?

Yeah a lot of them like Mattermost become surprisingly limited unless you pay. It's very annoying.
Mattermost's licensing is a little confusing, but from what I understand, you're only really super-restricted if you use the prebuilt binaries (which have a different license than the source code).

IIRC if you build it yourself it's pretty much all AGPL, with few limitations.

Many otherwise open-source chat apps are "open-core," they tie certain features to a subscription. Can be things like chat history, voice calls, video calls, but a very popular one is SSO and AD/LDAP integration.
This is awesome! Some feedback - I can't tell anywhere from the website if there is mobile support (which is a must-have if I want to consider moving my company or friends over to this)
Note that to send notifications to an iOS app, the app publisher has to send them. This means that they need to run an event forwarding proxy service (this is how Mattermost and Element/Matrix and presumably some/all of the ActivityPub clients do it), or selfhosting your server means you must also selfpublish your client app via the App Store and Apple’s developer program tax.
For Mastodon, each mobile app developer needs to have a "webpush relay server" to receive Mastodon's webpush notifications and transmit them to the platform's push service. For Android, Mastodon recently added support for the latest webpush standard which allows the app developer to directly register Google's webpush endpoint with Mastodon, removing the need for a relay. In all cases, push notifications are encrypted by the Mastodon server, and decrypted by the Mastodon client, so any intermediaries (relay server, push notification service) can not read their content.
Safari finally supports Web Push so maybe you can bypass all that nonsense.
Chatto currently commits to providing a strong PWA experience that also works great on mobile (including full support for voice and video calls, push notifications, the works.)

I am aware though that a lot of people would prefer an app that they can install, so this will be coming at some point -- just not a huge priority at the current point in the project's timeline.

Also, toss in a quick description. I couldn't tell quickly from the post or site what Chatto _is_. I guessed a vibe coded LLM TUI because that's the new hotness. In a world of Yggdrasil and Immich and Czkawka, a very brief intro helps!
What's the rationale for the dual licensing? It looks like the Go backend is AGPL but the TypeScript frontend is Apache 2.0.

Why not keep it all AGPL?

Backend under AGPL prevents someone hosting it as a service. AGPL specifies that hosting _is_ distribution. Therefore, anyone hosting it must do so with public code. This provides a soft form of exclusivity to run their own Cloud.

A frontend, permitting customizability, white-labeling, and so on, makes more sense to be more permissive.

Grafana is a solid example to illustrate why.

Moved from Apache to AGPLv3 in 2021 specifically so cloud providers couldn't host modified versions without contributing back, while keeping plugins Apache-licensed.

Prohibiting a user of your software from modifying it and using it to run their business goes against both freedoms 0 and 1.

This “users are obligated ‘give back’ the moment they make money with the gift they were given” is nonsense and anyone paying attention knows it. A business making money using free software doesn’t take anything away from the releasing organization.

The anti-commerce bent of a subset of the free software zealots hate business so much that they tried to smuggle a EULA into the free software community. It’s nonsensical. Furthermore, the AGPL has never once been tested in court.

Nobody is prohibiting you from using modified AGPL software to run your business.
> Prohibiting a user of your software from modifying it and using it to run their business goes against both freedoms 0 and 1.

It does not prohibit modifications - it just demands that those who exercise the freedoms share their modifications under the same license, and most businesses balk at that.

> The anti-commerce bent of a subset of the free software zealots hate business so much...

The root of the problem is actually the anti-free-software bent that business zealots have, because they want to be able take code for free and make money off of it without giving any of their changes back under the same terms. Things would be so much better if the moochers weren't trying to capture all of the value, but just some or even most of it.

You receive permission to use and modify a piece of software under conditions set by the creator. It is a license, not a gift. If you don’t like the conditions, use something else or create your own thing.

I will never understand these complaints. Not only do you want stuff for free, you also want to impose your preferred usage conditions on the creator. Where does this entitlement come from?

You’re confused. The author chooses to gift their software to the world when they choose a free software license.

Presumably people who choose the AGPL choose it because they believe it is a free software license. Either they should use an actual coherent free software license instead of one that is trying (and probably failing) to also be a EULA, or they should stop pretending that they are releasing free software.

> Prohibiting a user of your software from modifying it and using it to run their business goes against both freedoms 0 and 1.

Then it's good that it allows both modification and using it to run a business?

> This “users are obligated ‘give back’ the moment they make money with the gift they were given” is nonsense

But they are under no such obligation! They can make all the money they want and give nothing back. They can even modify the software to better serve their business. The only restriction is that if they do so, they have to make their modifications available. Which means they're way ahead of where they were before being given the initial software; why do you feel a software developer who decides to give the world a gift should be restricted in what gift they're giving? "Thanks for the chocolate, but the bar was too small so I didn't have enough left over for my kid to try some. Why do you hate my kid?"

> A business making money using free software doesn’t take anything away from the releasing organization.

First, that is false. They could damage the market for the original software. (And if they don't modify the software, then there's no problem in the first place.)

Second, why are you so hung up on the "making money" part, when that is explicitly allowed by the AGPL? It's just kind of bizarre -- it's a license that says over and over that you can charge for everything related to it, and you're complaining about it being hostile to people who want to charge money for things.

Thinking about it, I'm wondering if this is genuine confusion and you don't know what the AGPL is? If so, maybe start by searching for "charge" in https://www.gnu.org/licenses/agpl-3.0.en.html . It has nothing against "using it to run [a] business". There is no "moment they make money with the gift" that changes anything: you are explicitly allowed to charge for anything you like -- distribution, usage of the service, support, whatever.

I'm not sure what you are complaining about, AGPL is doing nothing against commerce and you are free to fork and sell a service using that fork. Just make sure to provide the code source of your fork to your user so they can also make their own forks, potentially making their own commercial services with them. It might be to most pro commerce licence I know.
GPL and AGPL don't even prohibit for-profit businesses from using software with those licenses, they just say you don't get to pretend it's your own intellectual property and privatize it.

It's not anti-commerce or anti-business to contractually prohibit selfish entities from absconding with public goods for private gain and refusing to contribute any public good back in the process.

Similar idea to public roads - if you want to use public roads that the rest of us enjoy, pay taxes like the rest of us do. Using public roads without paying taxes doesn't make you a savvy businessman, it makes you an amoral freeloader.

If you want an intellectual property moat, fund the labor to build it yourself. The world doesn't owe you a penny.

AGPL stops others from running a competing cloud service using the Go backend. It does nothing for the frontend except scare off enterprise users.
You can totally run AGPL code as a service. You can run it as a service unmodified or if you modify it, you just need to make the source available.
Very cool. I don't usually get excited for new chat apps, but I like the idea of having one frontend for multiple servers instead of pushing hard on p2p or federation.

I do also still like irc, but haven't used it much in recent years because most of the people I talk to are using discord now.

One front-end for multiple servers is how you end up reimplementing XMPP (bar federation) before you know it: servers are not guaranteed to run identical/compatible versions -> you bake versioning at capability level in the protocol -> you make clients and servers degrade predictably when that happens -> you write a standard to document it formally -> you invite around the table those authors of alternative client and server implementers and boom, you've got the X in XMPP, and the XEP standardisation process and the XSF to support it.
I bet this does a kind of "iframe" thing, where you're really just pulling in full web UIs, and they can be whatever they want. That's the impression I get from the comment about phone clients wrapping the web UI because there's no guarantee about what they will actually be.
I’m wondering about privacy tradeoffs. Looks like they’re similar to Discord where the chats won’t show up in web searches and you can’t read anything without joining. But if anyone can join, it’s not like Signal either and end-to-end encryption wouldn’t make sense.

(They do have end-to-end encryption for video.)

soooooo campfire then
Off the bat, it seems that campfire doesn't support voice/video calls. So no, not at all
They have some `curl | bash` type installation, which doesn't really fit my set-up. They say "email us if you have any questions", so I've emailed several months ago and I'm still waiting for a response.
Congrats for open sourcing it, looks interesting!

How does this compare to fluxer.gg though?

The part that I really liked about chatto is that it seems to be made very easily to self host which is something that I really appreciate actually.

I have been patiently waiting for fluxer, but honestly I just want to self host and have it available and fluxer has been sitting on that for a while
I'm the developer behind Fluxer – self-hosting is ready to use already [1][2][3], people are using it actively currently, and I'm currently working to make account switching across instances in the desktop app a reality. This, with a big voice update around the corner, will let us move much faster moving forward!

[1]: https://fluxer.app/blog/mobile-clients-and-fluxer-v2

[2]: https://docs.fluxer.app/operator/get-started/

[3]: https://github.com/fluxerapp/fluxer

Great work! Imo the most promising Discord alternative so far.

But I have a question, and maybe it is answered somewhere and I just couldn't find it, but is there currently a way to move a created community from e.g. the official hosting to self-hosted? I saw the mention about possible federation in the future, which would solve that (kind of), but currently it's not possible, I guess?

Thanks! And you're right, the future federation work is what will make it possible to implement support for transferring communities across instances natively.
I love Fluxer! Hampus is cool and what he's built is super impressive.

I would say the primary difference is that Chatto doesn't squarely aim for being a _Discord_ alternative. There are no plans for providing a Discord-compatible API (which I think Fluxer does.)

The other main difference is that Chatto is designed, on purpose, to serve individual communities from tiny deployments, instead of large mega-instances that power many communities. Chatto deliberately avoids content federation to remain compatible with business use cases, and also to stay simple enough so it can run from a single binary.

Couldn't help but smile because "chato" in portuguese means "boring", and this seems very easy to set up and use.

Here's to more boring software! :)

Can also mean annoying. As a general recommnedation, before naming a project or company something, always search whether it means something bad in the top 10 most spoken languages.

For portuguese/spanish, there is always a high chance of being a slang that is NSFW

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I’m going to say Nova to that.
Personally I've always found it funny that the widely used work software is called Slack which is very close to slacking (not working hard enough).
That’s where the name comes from, no?
Searchable

Log of

All

Communication &

Knowledge

In Spanish chato mean small, like a small nose (una nariz chata). In some contexts it can mean "dude".
I absolutely love boring software. It's a very, very rare quality nowadays.

"Boring" is not surprising, always acts like it's supposed to.

> Chatto aims to be the group chat application that you actually enjoy using.

So not like Discord or Slack?

> This is what it looks like:

Discord and Slack?

I mean, OK, it has EU hosting and that is good. But I see nothing obvious here that solves the noise and irritation of Discord and Slack.

I've been running Mattermost for a couple of years now and I'm content with it. It does feel a little bit clunky sometimes, but it's been stable and performant so I can't really complain. It can also feel a bit much sometimes. A bit too complex. A bit too feature-rich. But if I just ignore most of it, then it's good. I will say that Chatto looks nicer, appears to be simpler to setup and also has simpler licensing. Can it auto-update itself? That's something that's bad with Mattermost.
Does this federate with anything, like Matrix or XMPP? If it is locked into a single software, I fear nobody will ever switch to it (I have too many chat apps already!)
Looks great! How does it compare to Zulip? we self host zulip and are quite happy with it
So encrypted at rest but no E2EE, did I read that right?
Seems like it, but since you can self host it, you still get a lot more control over the data than using one of the aforementioned hosted offerings
Yeah, there are definitely valid contexts for hosting chat like this. E2EE has the benefit of not needing to trust the host, which I personally like but I can see this being fine or even wanted for lots of cases.
Yes, Chatto's core system does not use e2ee. This is by design; if there ever are e2ee features -- and chances are good they will, in some shape -- the encryption will be layered on top of that (encrypted message payloads and such.)
Looks great - is there any info on what server resources are actually required per feature or user count?
Still figuring out the numbers, so very hard to answer at the moment. Chatto is quite lightweight though; a fresh instance will run at tens of MB of RAM usage. RAM usage then scales with activity and CCU; on the Chatto HQ server, I'm currently seeing around 10 MB per additional connected user. I want this to be less, there's probably lots of room for optimization.

(You can scale Chatto horizontally across as many processes and servers as you need, so communities with tens of thousands of CCU should be perfectly feasible. But as you can imagine, there's precious little real-world proof for this yet :b)

Super happy to see someone take on slack. We just want a performant chat with simple features.

Slack integrations are overrated. Just give me webhooks.

Zulip has been open source since 2015.
Needs drop in voice rooms a la Discord or Slack's Huddle
It has audio and video call support in any room, so like huddle.