Convert FLAC to Opus Online

"Online converter" normally means uploading your file to someone's server, waiting in a queue, and downloading the result. This page inverts that: it loads FFmpeg compiled to WebAssembly into your browser and does the work on your own machine. You keep the convenience of online — nothing to install, works on any OS — without the upload.

A minute of FLAC is about 5 MB; the same minute as Opus is roughly 0.5. Across an album or a long recording that difference decides whether it fits on a phone. That matters here, because transfer is where server-based converters spend most of their time. With no upload and no download of the result, what's left is just the conversion itself: usually a second or two.

FLAC files typically come from CD rips, hi-res download stores, and archival libraries — and FLAC is lossless but poorly supported outside audiophile software — Apple's Music app won't touch it. Keep the FLAC. It's the archival master; the Opus is the copy that travels. Re-encode from the master whenever you need another format or bitrate.

Because it's a web page rather than software, the same converter runs on Windows, macOS, Linux, ChromeOS, iPhone, and Android — with nothing to keep updated and none of the bundled adware that comes with downloadable free converters.

The FLAC on your drive almost certainly started life in CD rips, and FLAC is lossless but poorly supported outside audiophile software — Apple's Music app won't touch it. Opus is the destination because it plays essentially everywhere — Discord recordings and every ordinary phone, browser, and player. A minute of FLAC is about 5 MB; the same minute as Opus is roughly 0.5. Across an album or a long recording that difference decides whether it fits on a phone. Because FLAC is lossless, encoding to Opus here is the clean, single-generation case — the encoder sees the whole original signal, so this Opus is as good as the format gets.