Why this exists

Every other free file converter on the web works the same way: you upload your file to their server, their server runs the conversion, you download the result. The trade-off most users don't think about: a copy of your file lives on their server, even if briefly.

That matters more for some files than others. A photo of your dog? Whatever. A bank statement, a court filing, a private chat export, a medical scan, an unreleased work draft? Those are files where having a copy land on a third-party server is at minimum an unnecessary risk.

twineconvert runs every conversion in your browser, using WebAssembly compilations of the same libraries the upload-based converters run on their servers (FFmpeg, libheif, pdfjs, mammoth, web-ifc, jsquash, and a few dozen more). The only difference: the conversion executes on your machine instead of theirs.

Practical implications: no upload progress bar, no daily quota, no file size cap, no signup, no email, no "upgrade to convert without watermark."

What's here

192 converters across 28 format families, the standard image / PDF / audio / video lineup, plus a long tail of professional and niche formats most generic converters don't bother with: OFX/QFX/QBO for personal finance, Apple Health export, Kindle clippings, GEDCOM (genealogy), BibTeX/RIS/NBIB (bibliography), ADIF (amateur radio), PGN (chess), IFC (BIM/architecture), DST/PES/JEF/EXP (embroidery machines), MIDI/MusicXML, ASE/ACO/GPL (color palettes), CUBE/3DL/CSP (color grading LUTs), STL/OBJ/3MF (3D meshes), and more.

Each conversion has a dedicated page with format explainers, a how-to, and the conversion UI itself. Browse all 192 →

Open source

The entire conversion engine is on GitHub. You can read every line of code that handles a file. You can fork it, audit it, run it locally without internet access, or fix bugs and submit them back. The 192-converter test suite (registry integrity, real-file conversion validation, round-trip equivalence, adversarial fuzz tests) runs on every commit.

What's next

The roadmap, in roughly priority order: more niche formats based on what users ask for, batch conversion (multiple files at once), a Progressive Web App install option for full offline use, and a Pro tier if/when there's clear demand for something paid (the free tier is permanently free, no bait-and-switch).

The engine eventually monetizes via display ads (AdSense → Mediavine when traffic is sufficient → Raptive at scale) on the SEO content areas of each tool page. The conversions themselves will never have ads, watermarks, or premium gates, that stuff erodes the core value proposition (convert files in your browser, fast, private, free).

Get in touch

Bugs, feature requests, format suggestions: open an issue on the GitHub repo. That's the canonical channel for everything.