Audio Compressor — Free Online Audio File Compressor
Free online audio compressor. Re-encode MP3, WAV, OGG or M4A files to smaller Opus audio at the bitrate you choose, or to a lighter WAV, right in your browse...
To compress an audio file, upload it, choose Compressed (Opus) with a bitrate or WAV with a lower sample rate and mono, then click Compress Audio and download the smaller file.
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Audio Compressor — Free Online Audio File Compressor. Free online audio compressor. Re-encode MP3, WAV, OGG or M4A files to smaller Opus audio at the bitrate you choose, or to a lighter WAV, right in your browser. No upload.
Use our free audio compressor to reduce the size of MP3, WAV, OGG or M4A files in your browser — nothing is uploaded to a server.
The file is decoded with the browser's Web Audio API and re-encoded to Opus (saved as WebM or Ogg, depending on what your browser's recorder supports) at Low (64 kbps), Medium (128 kbps), High (256 kbps) or a custom bitrate. Need a file that plays everywhere?
Choose WAV output with a lower sample rate and mono instead. Related: Base64 File Converter, Image Converter. Because the compress audio step runs on your own device, it suits voice notes, unreleased demos and confidential recordings.
The result panel shows the real original size, the real new size, the duration and the exact output type, and warns you when the result is larger than the original — for example when an already small MP3 is re-encoded at a high bitrate or written as WAV.
Opus output is recorded in real time, so longer files take as long as they play; WAV output is rendered in seconds.
Frequently asked questions
How do I use the audio compressor?
Drop an audio file on the upload area or click to browse, pick an output format, choose a bitrate (or a sample rate for WAV) and optionally Convert to mono, then click Compress Audio. When it finishes you see the original size, the new size, the change in percent, the duration and the output type, plus a player and a download button.
Does this tool really re-encode my audio?
Yes. The file is decoded with the Web Audio API and re-encoded in your browser. Compressed output uses your browser's built-in Opus recorder at the chosen bitrate; WAV output is rendered as 16-bit PCM at the sample rate you pick. The sizes shown are the real sizes of the file you download.
Why is the output WebM or Ogg instead of MP3?
Browsers do not ship an MP3 encoder. They can record Opus, a modern codec that sounds better than MP3 at the same bitrate, and save it as WebM (Chrome, Edge) or Ogg (Firefox). The download extension always matches the real format. If you need maximum compatibility, choose WAV output.
Why does compressing take as long as the song?
The browser recorder only accepts live audio, so the file is played silently into it in real time while a progress bar shows how far it has got. A 3-minute file takes about 3 minutes and can be cancelled. WAV output is rendered offline and finishes in a few seconds.
Why can the result be larger than my original file?
WAV is uncompressed, so a WAV made from an MP3 is usually larger unless you lower the sample rate and use mono. Re-encoding an already small MP3 at a high bitrate can also grow it. The tool then says how much larger the result is and suggests keeping the original.
Is my audio uploaded to a server?
No. Decoding, re-encoding, the player and the download all happen in your browser with local object URLs, so the audio does not leave your device.
How to use this online tool
Audio Compressor — Free Online Audio File Compressor is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.
Private processing in your browser
Audio Compressor — Free Online Audio File Compressor keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.
When this tool is useful
Use Audio Compressor — Free Online Audio File Compressor for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.
Practical tips
Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.