How to compress audio files
Use this page to select audio files, choose the output settings, and compress them in your browser. The audio-processing code has no audio upload path.
- Drop audio files onto the drop zone, or click browse files.
- Choose an Output format and Bitrate, or enable Target file size and enter a value in Target size.
- Review the estimate shown below the options; compression starts automatically when the input and settings are usable.
- Files are processed sequentially, with progress shown for the current file.
- Review the generated result controls and the before-and-after audio preview, then download the files you need.
Choose the output format and bitrate
The Output format menu offers MP3, AAC (M4A), OGG Vorbis, and WAV. The Bitrate menu offers 96, 128, 192, 256, and 320 kbps. Your selected bitrate affects the encoded output and the displayed estimate.
When you select WAV, the page disables the bitrate and target-size controls. The page describes WAV output as uncompressed.
Set a target file size
Enable Target file size, enter a value in Target size, and choose MB or KB. The tool calculates a bitrate from each file's duration, then constrains that value to 32–320 kbps. The requested size may not be achievable, so treat the displayed estimate as approximate.
Review results and downloads
After compression, the page can show the original size, compressed size, and savings for completed files. It also creates result controls and can display a before-and-after audio preview. These controls are generated after processing, so use the labels shown in the result row.
The page builds the ZIP archive locally from completed outputs and offers it through Download all as ZIP.
If compression fails
The file picker checks audio MIME types and several filename extensions. Passing that check does not guarantee that FFmpeg can decode the file. Compression can fail when the selected audio cannot be decoded or when the encoder does not load.
The page does not define a maximum file count, file size, duration, browser range, or practical memory threshold.
Memory and privacy limitations
Audio processing runs locally in the browser, and the compression code has no audio upload path. This does not establish that nothing else on the page makes a network request.
Source entries, source files, object URLs, and completed output blobs remain in browser memory until they are removed or the page is unloaded. The implementation does not guarantee that memory from a previous file is freed before the next file is processed.
Frequently asked questions
Why does it download 30 MB on first use?
The page displays Loading audio encoder (~30 MB, one-time download) while the browser loads the encoder. The local implementation does not confirm caching or instant loading on later visits.
What happens when I select WAV?
WAV disables the bitrate and target-size controls, and the page describes the output as uncompressed. It is not a way to restore quality already lost in a lossy source.
My audio format is not listed. Will it still work?
The drop zone lists MP3, AAC, OGG, WAV, FLAC, and more. The selection check only accepts audio MIME types and several extensions; it does not guarantee that FFmpeg can decode the file.
Is there a limit to how many files I can add?
The page code does not define a file-count limit. Files are processed one at a time, but source files and completed output blobs remain in browser memory until removed or the page is unloaded.
How accurate is target file size mode?
The tool calculates bitrate from the file duration and constrains it to 32–320 kbps. Because of that range, the requested target may not be achievable and the estimate is approximate.