About converter-epub.com
converter-epub.com is a free, browser-based EPUB converter. We turn DOCX, HTML, and TXT files into clean, valid EPUB 3 ebooks — without ever uploading your file to a server.
That's the whole pitch. The rest of this page is for people who want to know what's behind it.
What Problem This Solves
Every other "free" online file converter follows the same pattern: you upload your file to their server, their server processes it, you download the result, and — if the company is honest — your file gets deleted within hours or days.
For most files, that's fine. For unpublished manuscripts, internal business documents, medical notes, legal drafts, or anything containing personal information, it's a real risk. You don't know who's running the server, where it lives, what logs are kept, or whether the file was copied before deletion.
We built converter-epub.com because there was no good answer for the "I want a clean EPUB, but I don't want to upload my file" use case. Calibre handles it for desktop users. Nothing handled it well in the browser — until now.
How the Privacy Promise Actually Works
The whole tool is JavaScript. When you load this page, the converter code is downloaded to your browser. After that, every step — reading your file, parsing DOCX, generating EPUB, packaging the .epub file — happens locally on your device.
To verify this yourself, you can:
- Open the converter in your browser
- Open DevTools (F12 or Cmd+Opt+I) → Network tab
- Disable your internet connection (turn off Wi-Fi)
- Convert a file
If the conversion succeeds with no network, the site is genuinely client-side. We encourage you to actually try this — it's the only privacy claim that matters.
For the technical breakdown, see our privacy article, which covers the legal side (GDPR, HIPAA) and lists real case studies of people who regretted uploading sensitive files to "free" converters.
Who Built It
converter-epub.com is built and maintained by Jason Mai (about.me profile), an independent developer who also runs:
- apirank.vip — AI API pricing comparison (30+ providers, updated weekly)
- vpstier.com — VPS hosting reviews with real benchmark data
- threadgrab.com — Threads / X / Instagram video downloader, no install
- md2rich.com — Markdown to rich-text converter for X Articles / LinkedIn
All five sites share the same principle: open data, no sponsored rankings, no dark patterns. If a comparison site ranks a product, it's because the product is actually good — not because someone paid for placement.
The Tech Stack
The site is built on Astro and deployed to Cloudflare Pages. The conversion engine itself uses:
- mammoth.js for DOCX → HTML conversion
- JSZip for packaging the EPUB (which is just a zip file with .epub extension)
- Hand-written EPUB 3 template generation (no heavy library needed)
The site is fully open in the sense that you can read all the JavaScript it runs — no obfuscation, no minified tracking. The whole thing is a few hundred lines of straightforward code.
What It Supports Today
| Input Format | Output | Notes |
|---|---|---|
| DOCX (Word) | EPUB 3 | Headings, lists, bold, italic preserved |
| HTML / HTM | EPUB 3 | Standard tags supported |
| TXT | EPUB 3 | Paragraphs split on blank lines |
| PDF, MOBI, AZW3 | — | Not supported (use Calibre for these) |
For PDF-to-EPUB or batch conversion, we recommend Calibre (free, open source, desktop). For everything this site does support, we believe it's the fastest, cleanest option in 2026.
Contact and Feedback
Bug reports, feature requests, and questions all welcome. The fastest way to reach us is via the author profile on about.me — there's a contact form there.
For privacy-sensitive communication, please note that we have no record of what you convert on this site, so we genuinely cannot look up your file. If you have a problem with a specific conversion, you'll need to share the file again — and at that point, use whatever channel you trust.
Our Commitment
converter-epub.com will:
- ✅ Stay free for personal and commercial use, with no sign-up, no email, no watermarks
- ✅ Stay private — no uploads, no server-side processing, no tracking of your file content
- ✅ Stay open about how it works — no obfuscated JavaScript, no hidden analytics on the conversion itself
converter-epub.com will not:
- ❌ Add a "premium tier" that locks basic conversion features behind a paywall
- ❌ Start uploading your files "for faster conversion" or "for our AI training"
- ❌ Inject ads into the converted EPUB
That's it. Thank you for using converter-epub.com.