Audio Trimmer
Trim MP3, WAV, M4A, OGG, FLAC, or WebM audio in your browser. Waveform selection, sample-accurate cuts, optional fade in/out. Lossless WAV output. Voice memos and music stay on your device.
Drop an audio file to trim it
MP3, WAV, M4A, OGG, FLAC, WebM · never uploaded
How audio trimming works
ToolChop uses the browser's Web Audio API to decode the source file into raw 32-bit float PCM samples, displays a waveform built from peak amplitudes per bin, and lets you select a start-end region with sample-accurate precision. The selected segment is copied into a new WAV container with a hand-built 44-byte RIFF/PCM header — no compression, no quality loss from the trim itself.
Why a local audio trimmer matters
Audio files are almost always personal: voice memos, meeting recordings, podcast clips, music samples, speeches. All contain identifying audio (your voice, a colleague's voice) or copyrighted material. Uploading them to a third-party site just to trim off a few seconds is exactly the wrong workflow. ToolChop runs the entire pipeline in your browser.
What you can do
- Decode MP3, WAV, M4A (AAC), OGG (Vorbis / Opus), FLAC, WebM
- Sample-accurate trim with waveform visualization
- Optional linear fade in / fade out (0–2000 ms)
- Lossless WAV output (PCM 16-bit)
- Side-by-side source and result audio previews
Frequently asked questions
How do I trim an audio file online for free?
Drop your audio file, use the Start and End sliders to pick the segment you want, optionally add fade in/out, and click Trim. ToolChop encodes a new WAV file with just the trimmed segment. Preview before downloading. No account, no upload, no daily limit.
Does ToolChop upload my audio?
No. The audio is decoded by your browser's built-in audio engine (Web Audio API), trimmed locally, and re-encoded as WAV — all in your browser. Your file never leaves your device. This is the right approach for voice memos, music samples, and meeting recordings.
Why is the privacy story important for an audio trimmer?
Audio files in the wild are almost always personal: voice memos, podcast clips, meeting recordings, music samples, speeches, voice messages. All of these contain identifying audio (your voice, a colleague's voice, a private conversation) or copyrighted material. Uploading them to a third-party site just to chop off the start or end is a needless data path. ToolChop runs the trim locally.
What input formats are supported?
Anything the browser's Web Audio API can decode: MP3, WAV, M4A (AAC), OGG (Vorbis and Opus), FLAC, WebM. Coverage depends on the browser — Chrome, Firefox, Edge, and Safari all decode the common formats. FLAC and Opus support is universal in modern browsers.
Why does the output have to be WAV?
WAV is uncompressed PCM — the simplest possible audio container. Encoding to compressed formats (MP3, AAC) in the browser requires heavy WASM libraries (LAME, FDK-AAC) that often have licensing issues. WAV produces larger files (typically 10 MB/minute for stereo) but preserves perfect fidelity from the trim. Re-compress to MP3/M4A separately if size matters.
What does the fade in/out do?
It applies a linear volume ramp at the start and end of the trimmed segment, fading the audio in over the specified duration and fading it out at the end. Useful when trimming mid-song or mid-sentence to avoid abrupt clicks. 50–200 ms is usually plenty for music; 500–1000 ms feels natural for spoken word.
How accurate is the trim?
Sample-accurate. ToolChop computes the trim start and end positions to the exact sample (1/sample-rate of a second — for 44.1 kHz audio, accurate to ~22 microseconds). The slider granularity is 10 ms in the UI but the underlying operation is bit-perfect at the sample level.
Does trimming reduce audio quality?
No. The trim is a direct copy of the selected samples — bit-identical to the source within the selected range. The only quality consideration is that input decoded from MP3 has already lost information at encode time; the WAV output preserves whatever quality was decoded.
Can I trim a long podcast or audiobook?
Yes, but be aware of browser memory: Web Audio decodes the entire file into RAM as float32 samples. A 1-hour 44.1 kHz stereo file is ~1.5 GB in memory. Most modern browsers handle this fine; very long files (4+ hours) may slow down. For huge files, split first using desktop tools, then trim each segment here.
Why is my output file so much larger than the source?
Because WAV is uncompressed and most sources (MP3, M4A) are compressed at ~5–15× ratios. A 3 MB MP3 decoded and trimmed to WAV might be 30 MB. If file size matters more than quality preservation, use a separate MP3 encoder after the trim — or upload to your destination if it accepts WAV.
Can I extract just the audio from a video file?
Partially. Drop a WebM or MP4 audio track and the browser may decode it as audio-only. For full video-to-audio extraction with format conversion, you'd need ffmpeg.wasm — a heavier WASM bundle we may add later for video-aware tools.
Why use ToolChop instead of an online audio trimmer that uploads my file?
Privacy. Audio recordings are deeply personal — voice memos, meeting recordings, private podcasts, music samples. Uploading them to a third-party server just to chop off the first 5 seconds is exactly the wrong workflow. ToolChop runs the trim in your browser. DevTools → Network confirms no request fires.