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Show HN: Extend UI – open-source UI kit for modern document apps (extend.ai)

252 points by kbyatnal ↗ HN
We're open-sourcing 14 components & examples today for PDF, DOCX, and XLSX viewers, plus bounding box citations, file upload, e-signature, and more. It's MIT licensed and fully customizable.

Demo video here: https://share.extend.ai/kRmSGKRF

When we started, we tried every file viewer and document component library we could find. Unfortunately, none of them had all the functionality (and polish) that we wanted, so we ended up building our own for https://extend.ai/. It was only ever meant to be internal, but enough customers kept asking for it that we decided to open source it.

It's useful for building document processing agents, real-time user facing document intake flows, or all kinds of internal tooling.

We naively thought this would be a solved problem. Turns out, making PDF/XLSX/DOCX viewers that work at scale is not trivial...we use and maintain it for Extend ourselves, so we've fixed a lot of edge cases that came up while running millions of pages / day through our own system. Our hope is that with our resources + community support, it'll keep getting better over time.

38 comments

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spankalee
These should really be web components. Leaving out every framework other than React is really bad for the web.
andrewlu0
thats fair and definitely something we can try supporting in the future. we started with React because of how familiar models are with shadcn and tailwind

we hope this can be useful for people building in React though!

digitaltrees
Then build it yourself. They do work for free, give it to the world, and your response is: do it differently the way I want.
warthog
really like these - curious how the xlsx editor and viewer is built in that what kind of headless spreadsheet?

could not have been easy

CraigJPerry
Those bounding box demos are decent.

By quirk of fate i've spent the past 2 days prototyping some stuff on pdfjs. Just trying to figure out a game plan for handling bounding boxes in the face of page zooming, different resolutions etc. etc. I can't see it mentioned whether the components are virtualising pages (as in reusing dom elements as document pages scroll by). I guess i just learned what i'll be exploring tomorrow then...

egeozcan
Why doesn't it mention anywhere that they are React components?
hobofan
Thanks, that looks awesome! We were looking to add DOCX and XLSX preview to our app, and were planning to do server-side conversion to PDF (which seems to be what most other apps resort to) due to the lack of good libraries to render it, and this is exactly what we were looking for! :)
dvt
Super cool. Working on a local AI tool specifically for document workflow automation (where context = screen/web/folders/files), and this could come in super useful. I do most of the PDF/DOCX/etc. parsing natively in Rust, but having a nice way to see the output without spinning up Word or Powerpoint is a huge leap.

Thanks for releasing publicly.

stinger
Does it/will it support Markdown files?
plastic041
Looks clean and works fine, but it needs optimization. Clicking "Type" in the "schema builder" example takes 1~2 seconds to open the popover in the landing page(macbook pro m4). I think its because there are lots of heavy components, but still it's too slow.
qreoct
Cool project! I was playing around with the Excel viewer - the docs claim "Search across sheets and cell ranges", but I can't seem to trigger search functionality and the browser search bar can't find contents on cells.

Is this a known issue?

andrewlu0
just added an example implementation in the xlsx viewer for search, but the code is yours to modify and customize. react-xlsx should expose the necessary functions to implement a custom search (by workbook/sheet etc...)
pea
Looks cool but your home page heavily lags on my mbp m3 pro - you should maybe be lazy loading vs loading all your components upfront
promiseofbeans
How is your PDF coverage? They are notoriously difficult things to render, with endless edge cases. Mozilla’s PSD.js is the status quo here, so what do you do better than them?
carlosjobim
Excellent that you offer Miller columns, one of the best tools for computing and information browsing, and management. The world should run on Miller columns.
mklifelife
Looks great.

I'm curious whether the primary users are AI-native document products or more traditional SaaS applications.

The document-app niche feels increasingly important with the rise of AI workflows.

sails
primary use is Document processing automation, or Intelligent Document Processing (IDP)
rolls-reus
Mind sharing a link to the source code? i couldn’t find it on the website.
sails
Experienced the same nightmare a few times over with citations.

React/next is limiting, we have rebuilt this for angular and now redid it again using lit for better compatibility. Our old one is very similar to this.

Loading citations for each field across 1000s of pages, colliding citations for all the messy formats, zoom, rotate etc. what a mess!

Great that you took the time to MIT this as it would have saved us many hours, though I think today Fable + Codex makes it pretty quick

I could recreate these in lit as a fork, would be very useful to have the full set

iamsaitam
The performance on the site is truly terrible, the top animation was probably going at 5fps when scrolling.
lionkor
The performance is quite bad. There are some basics missing or broken.

- no caching for file previews

- no sorting by date in the file picker

- no sorting by size in the file picker

- no sorting by file type in the file picker

- no search in the file picker

- cant enter a folder in the detail view (only expand) in the file picker

- cant go to page (by page number) in the document viewer

- after clicking a button in the document viewer, focus is lost on the document and arrow keys, space, pgup/pgdown dont work until the document is clicked again

- cant select text in the document viewer, unless I search first, in which case it then works

This is after looking at the file picker and document viewer less than 3 minutes(!!!). I gave up after that. Getting 80% of a file picker is easy, getting the last 20% done, so that it's on par with existing software, is not.

Very very odd to have things look this polished, yet be this terrible functionality- and performance-wise. These are not random quirky new ideas I'm having, these have been basics that work in every single file picker and document viewer since the early days of UI, before the web.

whitephoenix
It looks really great! But, from what I can see, it’ll need some work on optimisation. Good luck with this project, guys!