A powerful online MP3 compression tool that runs entirely in your browser. No file uploads to any server.
Try it online: https://mp3-compressor.tools.ioatlas.com/
Unlike other online MP3 compressors, this tool provides:
- Detailed File Info Preview - View complete audio metadata before compression (duration, bitrate, sample rate, channels)
- Rich Compression Options - 8 preset profiles + fully customizable parameters
- Real-time Estimation - Preview estimated file size and compression ratio before processing
- 100% Local Processing - Files never leave your device, ensuring complete privacy
Automatically analyzes and displays after upload:
| Info | Description |
|---|---|
| File Size | Auto-converted to B/KB/MB |
| Duration | MM:SS format |
| Bitrate | Original bitrate (kbps) |
| Sample Rate | Original sample rate (Hz) |
| Channels | Mono/Stereo |
8 preset profiles covering different use cases:
| Preset | Bitrate | Sample Rate | Channels | Best For |
|---|---|---|---|---|
| Near Lossless | 320 kbps | Original | Stereo | Hi-fi music archiving |
| High Quality | 256 kbps | 44.1 kHz | Stereo | Music collection |
| Standard | 192 kbps | 44.1 kHz | Stereo | Everyday listening |
| Medium | 128 kbps | 44.1 kHz | Stereo | Balance quality & size |
| Compact | 96 kbps | 32 kHz | Stereo | Save storage space |
| Voice | 64 kbps | 22.05 kHz | Mono | Podcasts/Voice content |
| Minimal | 32 kbps | 16 kHz | Mono | Smallest file size |
| Custom | Adjustable | Adjustable | Adjustable | Full control |
In "Custom" mode, freely adjust:
- Bitrate: 32, 48, 64, 80, 96, 112, 128, 160, 192, 256, 320 kbps
- Sample Rate: 11025, 16000, 22050, 32000, 44100, 48000 Hz
- Channels: Mono / Stereo
- Drag & drop file upload
- Real-time processing progress
- Auto-generated filename with compression parameters
- Multi-language support (English, 繁體中文, 日本語, Deutsch, Français)
- React 19 - UI framework
- TypeScript - Type safety
- Vite - Build tool
- FFmpeg WASM - Audio processing engine
Run these commands from the tools repository root, then open /mp3/.
# Install dependencies
bun install
# Start dev server
bun run dev
# Build for production
bun run buildThis tool uses the WebAssembly version of FFmpeg to process audio files directly in your browser:
- Web Audio API parses audio metadata
- FFmpeg WASM handles the actual compression
- All processing happens locally - files never leave your device
Application code: MIT.
Third-party components retain their own licenses. The @ffmpeg/ffmpeg wrapper
and @ffmpeg/util are MIT-licensed; the separately loaded @ffmpeg/core@0.12.6
contains FFmpeg and external libraries under their respective licenses.
See Third-party notices for the exact source and build references.