About this tool
The FreeSeerPDF audio converter converts sound files between MP3, WAV, OGG, M4A (AAC) and FLAC, with a visual waveform editor for trimming. Drag the highlighted region on the waveform to cut silence or extract a clip, choose your output format and bitrate (128 to 320 kbps), and convert.
The tool is powered by ffmpeg — the same engine used by professional software — compiled to WebAssembly so it runs inside your browser. The engine is downloaded once (about 32 MB) the first time you use the tool and is then cached, and your audio files themselves never leave your device.
How it works
- Drop in an audio file — almost any format is accepted, including voice notes.
- Optionally trim it by dragging the selection on the waveform, and pick the output format and bitrate.
- Click Convert audio, preview the result in the built-in player and download it.
Frequently asked questions
Why does the first conversion take a moment to start?
The audio engine (ffmpeg compiled to WebAssembly, ~32 MB) is downloaded once on first use. After that it is cached by your browser and starts instantly.
Can I convert WhatsApp voice notes to MP3?
Yes — voice notes (OPUS/OGG or M4A) are fully supported. Drop the file in, choose MP3 and convert.
Which bitrate should I choose for MP3?
192 kbps is a great balance of quality and size for music. Use 128 kbps for voice recordings and 320 kbps when you want maximum quality.
Is my audio uploaded to a server?
No. The conversion runs entirely on your device — your recordings, songs and voice notes stay private.
How precise is the trimming?
Trimming is accurate to a tenth of a second. Drag the region handles on the waveform for a rough cut, then fine-tune the start and end times in the number fields.