A Lemonade Stand That Charges for Ice
Here's the setup. Your library is EPUBs. Your Kindle only speaks MOBI. Your AI reading assistant only eats PDF. Three formats, one file, and somehow the internet still fails at this. Every "free" converter I tried, CloudConvert, Convertio, FreeConvert, dangles the free part right up until you hit a file size cap, a queue, or a very sudden upsell. It's a lemonade stand that charges for the ice.
That's not really about e-books. It's the whole free-tier internet: monetize the friction, then sell you the fix. So I stopped participating. One hour, one local Flask app, and now converting a book costs me nothing but electricity. No cloud, no subscription, no uploading my reading habits to a server that will absolutely sell that data eventually.
The Boring Stack, on Purpose
Nothing here was invented. It was assembled, on purpose, from parts that already work.
• Backend: Python and Flask. Not exciting. Also never once the reason something broke.
• The actual conversion engine: Calibre's `ebook-convert`, because Calibre has been solving this exact problem since before "vibe coding" was a phrase, and reinventing it would just be ego.
• Frontend: plain HTML, CSS, and a little JavaScript, wrapped in a "bookish" theme, because a tool for reading books shouldn't look like a spreadsheet.
The Actual Point
It converts e-books. That's the whole feature list. But it also proves something more useful: most "digital convenience" fees are a tax on not knowing you could just build the thing. This is what happens when a clear annoyance meets an hour of free time and zero patience for another upsell.
You can build the tool instead of renting it. And on a good day, the most satisfying response to a broken system is a quiet `python app.py` running in your own terminal, converting your own files, on your own machine, for free.