OfflineMP3

OfflineMP3 is in public Beta. It converts one selected audio track from a video you already have into an MP3. The work runs in your browser at app.offlinemp3.com. OfflineMP3 does not upload that file to its own server in order to convert it. No account is required. Free to use during Beta is not a promise that the product will stay free, that use will have no cap, or that the business model will stay the same. OfflineMP3 is operated by Bo Zhang.

Video to MP3Turns one selected audio track from an authorized MP4, M4A, M4B, MOV, or WebM file into a verified 192 kbps CBR MP3. Ordinary speech, music, and other audio are included. The conversion is lossy. There is no public file-size or duration limit yet.

Open the converter

What it does

Video to MP3 is the only tool on this site. You open the converter, choose a local MP4, M4A, M4B, MOV, or WebM file, and pick one audio track. The page inspects the file on your device. When the container, the audio codec, the channel layout, and the duration are inside the current public range, it re-encodes that track to a 48 kHz, 192 kbps constant-bitrate MP3. There is no quality slider and no loudness control. The conversion is lossy. Tags, chapters, and cover art from the video are not copied into the MP3.

Support is decided from the file contents, not from the filename extension. MP4, M4A, M4B, and MOV need AAC-LC audio. An M4A or M4B file may contain only audio, which is how many phone voice memos and iTunes audio files are stored. WebM needs Opus audio. Mono stays mono. Stereo stays stereo. A layout labelled 5.1 is downmixed to stereo, and the low-frequency effects channel is left out. Other layouts are refused before encoding. The Video to MP3 page is the short version of this. The guides go further into formats, bitrate, privacy, browsers, and failures.

Three steps

Open the converter. These pages on www.offlinemp3.com explain the tool. The button Open the converter goes to the processing app, which is a separate site. Use a desktop copy of Chrome or Edge. That app blocks phones and tablets, and it blocks a browser that does not expose a Worker and WebAssembly. The browser guide describes the check and the memory the conversion can use.

Choose the file and the track. Select a file from your computer. The page reads it locally and lists each audio track with the language, title, channel layout, and default flag when the file provides them. A declared default is pre-selected. A file with only one audio track selects that track even when the file sets no default flag. If several tracks exist and none is the default, you have to choose one. Choosing a track does not start conversion. Press Convert selected track when the track you want is selected.

Wait for verification, then save. Preparation, inspection, and verification do not pretend to be a percentage. During encoding the page shows elapsed time and an approximate percentage that stays at or below 99% until verification succeeds. When the browser offers a save dialog, Save completed means the verified file was written and that file was closed. Download MP3 can only be called Download started, because the browser does not confirm that a download was closed. If you dismiss the save dialog, the verified result stays so you can try the save again without converting a second time.

What stays on your device

Your media file stays on your device. That sentence is about the video you select for conversion. It does not mean the website never uses the network. The converter program is downloaded from the processing site, the host that serves the pages sees ordinary connection data such as an IP address, and a content page may request a Google ad when the rules in the privacy policy all hold. The processing app does not load an ad script and does not set an advertising cookie.

You do not create an account, and these pages do not ask for your name or a payment card in order to convert a file. The converter does not send a diagnostic event. It can show timing and memory figures on your own screen. Those figures are not uploaded. The privacy policy describes the privacy-minimized diagnostic event that would exist only if a share control is added later, and the diagnostic deletion credential that would belong to that event.

Questions people ask first

The output is always a 192 kbps MP3. This tool does not switch the file to 128 kbps or 320 kbps. The bitrate guide explains what those rates mean, and why a higher rate is still a lossy encoding.

A file whose name ends in .mp4 can still be refused. The inspector looks inside the file. The formats guide lists the codecs and channel layouts that pass, including the rule that every audio track in the file has to be a supported codec, not only the track you hoped to select.

A refused file does not produce a saveable MP3. The page names the reason and a next step. Some files pass inspection and still fail the later verification, so there is still nothing to save. The troubleshooting guide walks through those cases. Ordinary speech, music, and other audio in a supported file can be saved. Verification does not require a special tone, a test pattern, or any particular number of loud segments. The MP3 must be non-empty, it must decode completely, and its decoded duration must match the selected track. The FAQ collects the short answers.

Guides