So this was not supposed to become a product. I needed to merge some EPUBs, I didn't want to open Calibre for that, and every online tool I found was full of ads or wanted me to create an account to merge two files, or was just weird in a way. So I started building something quick on Cloudflare Workers with Claude Code.

One tool became two, two became five, and now there is nine of them. Merge, split, compress, EPUB to PDF, PDF to EPUB, metadata editor, validator, a reader, and I just added an AI cover generator with FLUX because why not at this point.

The thing that surprised me is how cheap it is to run. Workers free tier is 100K requests/day. D1 is free. KV is free. Analytics Engine is free. Workers AI has a free tier too. I pay for the domain and that's basically it(And the Claude code subscription obviously). When I realized the running cost was almost nothing I told myself I should just put it online and let people use it.

I added a Pro plan at $9/mo for people who need bigger files (200MB vs 10MB) or want the branding removed, but honestly the free tier does the job for most use cases. This would also be useful if the users vastly surpass the free tier but I don't think that's gonna happen.

The stack is very simple on purpose. Cloudflare Workers with Hono, vanilla JS for the frontend (no React, no build step), jszip and pdf-lib for the file processing. Everything runs in memory because Workers don't have a filesystem. The 128MB memory limit and 30s CPU timeout forced me to keep things clean which I actually enjoyed.

There is also a REST API and an MCP server if you want to plug it into AI workflows.(I <3 agents)

https://epublys.com

I might have to do a few more things related to security but there isn't a single thing to steal, the files aren't saved anywhere, not even in cache and there is no secret admin panel to do ??? or api keys hanging around.

I'm happy to talk about building on Workers, the constraints, or how Claude Code works for this kind of project. Also curious what other tools would be useful. I can add things pretty fast now that the base is there and honestly it's very fun, especially when you're not a dev like me.

So it's the start of something and I truly believe that the era of 'selfware' is there. Even if no one ever use this app I'll be extremely happy because my needs are covered. (also I wanted to post on 'Show HN:' after years of lurking but it seems that it's blocked for 'new' account now)