Free Online Audio Tools — Convert, Trim, Record & Transcribe
Seven browser-based audio tools for converting formats, trimming recordings, recording new audio, and transcribing speech to text. All processing uses the Web Audio API and runs entirely in your browser — no audio files are uploaded.
Each Audio Tool Explained
Any Audio to MP3
The universal audio converter — accepts any audio format your browser can decode and outputs MP3. MP3 is supported everywhere: every smartphone, car audio system, streaming platform, podcast host, and email client handles MP3 without issues. WAV files are lossless and therefore very large (a 1-hour WAV recording is typically 600 MB+); converting to MP3 reduces that to 50–100 MB with no perceptible quality difference at standard bitrates.
WAV to MP3
WAV (Waveform Audio File Format) is an uncompressed audio format used by professional audio equipment, recording software, and Windows as its default audio format. It produces perfect audio quality but extremely large files. MP3 is a lossy compressed format that achieves a 10:1 compression ratio at 128kbps while preserving near-CD quality for most listeners. Use this converter when you need to share, upload, or email a WAV recording.
M4A to MP3
M4A is Apple's audio container format, used by iPhone voice memos, iTunes purchases, and GarageBand recordings. While M4A plays natively on Apple devices and in iTunes, it is not universally supported — older audio players, some car systems, and certain podcast platforms require MP3. Converting M4A to MP3 ensures the audio plays anywhere without quality loss perceptible to most listeners.
WAV to M4A
M4A (AAC) is the modern successor to MP3 — it produces smaller files at the same quality level. A 128 kbps M4A sounds roughly equivalent to a 192 kbps MP3, saving 20–30% in file size. M4A is the native audio format for Apple devices, and is supported on all modern Android devices, Windows 10+, and web browsers. Use this converter when you want the best quality-to-size ratio for distribution on modern platforms.
Audio Trimmer
Trims an audio file to a specific start and end time without re-encoding. Common use cases: removing silence from the beginning or end of a recording, cutting a clip for use in a presentation, extracting a specific segment from a longer interview or meeting recording, or creating a ringtone from a song. The trimmer uses the Web Audio API to slice the audio data at the specified timestamps without needing to re-encode the entire file.
Voice Recorder
Records audio from your microphone using the browser's MediaRecorder API. No app or software installation required. The recording runs entirely in your browser tab — you can record a voice memo, note, or message and download it immediately as MP3 or WAV. The microphone is only active while the recording is running; the browser shows a clear indicator when the microphone is in use.
Audio to Transcript
Transcribes spoken audio to text using the browser's built-in Web Speech API (available in Chrome and Edge). The audio is processed by your browser's speech recognition engine — in Chrome, this uses Google's speech recognition service, but only the audio stream during active transcription is sent, not your file. For fully private transcription without any network transmission, use the Voice Recorder to capture speech directly and transcribe in real time.
Audio Format Comparison
| Format | Type | Typical Size (1 hr) | Best For | Compatibility |
|---|---|---|---|---|
| MP3 | Lossy compressed | ~57 MB at 128kbps | Sharing, podcasts, email | Universal |
| WAV | Uncompressed | ~600 MB | Recording, professional audio | Universal but large |
| M4A | Lossy compressed (AAC) | ~55 MB | Apple ecosystem | Apple-native, limited elsewhere |
| FLAC | Lossless compressed | ~200 MB | Archiving, audiophile | Limited — needs dedicated player |
| OGG | Lossy compressed | ~45 MB | Web streaming, games | Browser-native, not media players |
| AAC | Lossy compressed | ~50 MB | Streaming, mobile | Good — standard on iOS/Android |
Audio Quality vs File Size — What You Need to Know
Audio compression works by removing frequencies that the human ear is least sensitive to. At 128kbps MP3, most listeners cannot distinguish the output from the original WAV in a standard listening test. At 64kbps, compression artifacts become audible in music but are acceptable for voice recordings.
Choosing the right bitrate:
- Voice recordings, podcasts, meetings — 64–96kbps MP3 is sufficient. The frequency range of spoken voice is narrow, and compression is very effective.
- Music for general listening — 128–192kbps MP3 is standard. Most streaming platforms deliver at 128–256kbps.
- Professional audio work — keep as WAV or FLAC throughout production. Convert to MP3 only for final delivery.
- Transcription source files — quality matters less for transcription than for listening. Clear speech at 64kbps transcribes as accurately as 320kbps.
🔒 Privacy — Audio Recordings Are Sensitive Content
Audio recordings can contain private conversations, confidential meetings, medical consultations, legal discussions, and personal voice data. Uploading audio files to a cloud conversion service means that content travels to and is temporarily stored on a third-party server.
All audio tools on this site use the Web Audio API and MediaRecorder API — both built into modern browsers — to process audio locally. No audio data is transmitted to any server. The Audio to Transcript tool uses the browser's built-in speech recognition; in Chrome, the active audio stream is processed by Google's speech API, but your audio file is not uploaded — only the live microphone stream during active transcription is used.
For maximum privacy when transcribing sensitive recordings, use the Voice Recorder tool to re-record directly into the browser and transcribe in real time rather than uploading a pre-recorded file.