Is my file uploaded when converting MP3 to FLAC?

No. The conversion runs entirely in your browser. The file never leaves your device, there is no server to upload to, and the page works offline once loaded.

Is MP3 to FLAC conversion free?

Yes, with no account, no watermark and no file limit per day. frogConvert is open source and there is no server cost to recover, because your device does the work.

How large a file can I convert?

Up to 2 GB for a single file, 500 MB total per batch, and 300 files at once. The practical limit is your device's memory, since everything is processed locally.

Convert MP3 to FLAC

Stores MP3 audio in a lossless container, which prevents any further generation loss.

Convert MP3 to FLAC →

Runs on: FFmpeg, compiled to WebAssembly, running in this tab
Steps: Direct, a single conversion
Input: .mp3 · audio/mpeg
Output: .flac · audio/flac
Uploads: None. The file never leaves your device.

What to expect

FLAC can hold the audio perfectly but the frequencies MP3 removed are already gone. The file gets much larger with no quality gain.

Why convert MP3 without uploading

Most online converters take your file, send it to their servers, convert it there and hand back a download link. That means your document sits on someone else's disk, subject to their retention policy and their breaches. It also means you cannot use them offline, and cannot use them at all for anything confidential.

frogConvert does the conversion in the page itself, with FFmpeg compiled to WebAssembly. There is no upload step because there is no server. You can disconnect from the network and it still works.

About the formats

MP3

The format that made digital music portable, using perceptual coding to throw away sound judged inaudible. Universally supported and comfortably outperformed by every codec designed since. More about MP3 files.

FLAC

Free Lossless Audio Codec compresses audio to roughly half its uncompressed size and decodes back bit-for-bit identical. The obvious choice for archiving a collection you may re-encode later. More about FLAC files.

Common questions

Is my file uploaded when converting MP3 to FLAC?: No. The conversion runs entirely in your browser. The file never leaves your device, there is no server to upload to, and the page works offline once loaded.
Is MP3 to FLAC conversion free?: Yes, with no account, no watermark and no file limit per day. frogConvert is open source and there is no server cost to recover, because your device does the work.
How large a file can I convert?: Up to 2 GB for a single file, 500 MB total per batch, and 300 files at once. The practical limit is your device's memory, since everything is processed locally.
What is lost converting MP3 to FLAC?: FLAC can hold the audio perfectly but the frequencies MP3 removed are already gone. The file gets much larger with no quality gain.