About

a → b is a free file converter that does one thing: take a file in format a, give you back a file in format b, in your browser, without sending your data anywhere.

Why does this exist?

Most online file converters upload your files to their servers. Even when they say they don't keep them, you have to take their word for it. I wanted a tool I could trust with personal documents — contracts, tax forms, scanned IDs — without that leap of faith. So I built one where the privacy promise is enforced by the architecture, not a policy page: there is no upload endpoint on the site at all.

How is this free?

It costs almost nothing to run. The site is static HTML and JavaScript hosted on Cloudflare. Conversion happens on your device, so there's no server to pay for. There are no ads. There's no data to sell. If you'd like to support the project, you can buy me a coffee. Optional, never asked twice.

How is this fast?

Modern browsers can do a surprising amount. Image conversion uses the Canvas API. PDF tools use pdf-lib and pdf.js. Compress PDF additionally runs qpdf compiled to WebAssembly, plus mozjpeg for image re-encoding, in a Web Worker so the page stays responsive on large files. The whole pipeline ships as a single static site — no installs, no extensions, no accounts.

Open source

The code is on GitHub. Anyone can audit it, fork it, or open an issue. MIT-licensed.