What Wave is
Wave (wavemp4.com) is a free video converter that runs entirely inside your browser. You drop in a video file; Wave converts it to MP4 (or extracts the audio as MP3) using a WebAssembly build of FFmpeg loaded into the page. The file never leaves your device. There is no account, no sign-up, no watermark, and no paid tier.
Why it exists
Every popular free video converter works the same way: you upload the file to a server, the server runs FFmpeg on it, and you download the result. That flow has become invisible to most users, but it is an upload. Video files carry metadata (timestamps, sometimes GPS, sometimes screen contents), and once they land on a third-party disk you are trusting a privacy policy rather than a technical guarantee.
By 2023, browsers had enough of the necessary pieces (WebAssembly, Web Workers, streaming file APIs, WebCodecs) to run a real video converter locally. Wave is a straightforward attempt to build that: a small, focused tool that does one job on your device instead of somebody else's.
How it works, in one paragraph
The page loads a WebAssembly build of FFmpeg (about 30 MB, cached after the first visit). When you drop a file, Wave inspects the streams and picks the cheapest path: a remux that copies the streams into MP4 when the codecs already fit, or a re-encode when they don't. Re-encodes prefer the browser's WebCodecs H.264 encoder (hardware-accelerated on most machines) and fall back to an LGPL MPEG-4 Part 2 encoder inside the wasm engine. Audio extract uses libmp3lame. See the moov atom explainer for the fast-start details we apply to every MP4 we produce.
Licensing
The bundled FFmpeg build is LGPL only, with GPL encoders (libx264, libx265) deliberately excluded so the whole distribution can stay license-clean. Attributions for every third-party component are in the site's THIRD_PARTY_LICENSES.md file.
Who's behind it
Wave is an independent project maintained by developers who wanted a video converter they could actually trust with their own files. The site is hosted on Cloudflare Pages. There is no company behind it in the "startup with employees and a business model" sense, and no plans for that to change.
Contact
Reach us at technorology@gmail.com for bug reports, format requests, security disclosures, or press. We do not run a support desk; response times are best-effort.
Roadmap, informally
Batch conversion, multi-track audio passthrough (AC-3 5.1), and MP4 chapter editing are the most-requested features and the most likely additions. Adding video-to-video conversions beyond MP4 (MKV out, MOV out) is not on the roadmap; Wave stays a single-purpose tool by design.