Video Trimmer
Trim mp4, webm, mkv, and mov videos in your browser with ffmpeg.wasm. Lossless (-c copy) for instant cuts at keyframes, or frame-accurate re-encode when you need precision. No upload, no signup.
Interactive tool
ffmpeg.wasm engine loads on first run (~32 MB)
The engine is cached for the rest of your session. Every transcode runs entirely in your browser: files never leave your device.
Threading: detecting…
Drop a video here
Up to 250 MB / 5 minutes. The file never leaves your browser.
What is the Video Trimmer?
A free, in-browser video trimmer powered by ffmpeg.wasm. Pick a start and end on the scrubber, choose lossless (-c copy) for instant cuts or frame-accurate re-encode for precision, and download. No upload, no server, no signup.
How to Use the Video Trimmer
- 1Drop a video file (mp4, webm, mkv, mov)
- 2Drag the start and end thumbs on the timeline to your cut points
- 3Pick Lossless (fast, snaps to keyframes) or Frame-accurate (precise, slower)
- 4Click Trim: ffmpeg.wasm loads on first run, then is cached
- 5Preview and download the trimmed clip
Key features
Dual-thumb timeline scrubber
Drag both ends on a single track for an instant visual cut
Numeric inputs as a backup
Type the start, end, or duration directly in mm:ss.cs format
Lossless mode
Stream-copy from the nearest keyframe: finishes in seconds, perfect quality
Frame-accurate mode
Re-encode with H.264 CRF 18 for an exact start frame, no keyframe rounding
Multi-threaded ffmpeg.wasm
Uses SharedArrayBuffer when available for 5-10x faster re-encodes
Cancel any time
Hard-terminate the worker mid-encode with a click
100% private
No upload, no signup, no logs: the video never leaves your browser
Why Trim Locally Instead of Online?
Cloud trimmers upload the full file, queue it, and frequently watermark or quality-limit free output. Trimming locally is faster on anything under ~100 MB, completely private, and free of watermarks.
Common use cases
- Cut a 30-second highlight from a screen recording
- Remove dead silence at the start or end of a meeting capture
- Shorten a phone clip to fit Twitter, Instagram, or TikTok
- Split a long podcast video into smaller social-friendly chunks
- Discard a fluffy intro / outro before uploading to your CMS
Lossless vs Frame-accurate
- Lossless: -c copy with -avoid_negative_ts. Cuts at the nearest keyframe; quality is byte-identical to the source.
- Frame-accurate: libx264 -crf 18 + AAC. Decodes and re-encodes, so the cut is exact to the millisecond.
- Rule of thumb: try lossless first; if the cut is off by half a second, switch to frame-accurate.
Keyframe alignment
Modern recordings typically place a keyframe every 1-2 seconds. Lossless mode snaps to the keyframe that precedes your chosen start, so the actual cut may begin up to a couple of seconds earlier than the slider position. Frame-accurate mode bypasses this entirely.
Output container
The trimmed file keeps the source container (mp4 → mp4, webm → webm, etc.). Use the Video Format Converter afterwards to change container or codec.
Tips & best practices
Lossless trims are nearly free
Cutting 10 minutes off a 30-minute mp4 with -c copy typically finishes in under 2 seconds: try it first.
Use frame-accurate for music videos
Lossless mode can drift the audio start by up to one keyframe interval. Frame-accurate mode preserves audio-video sync exactly.
Trim before compressing
Always trim first, then compress: fewer frames means a smaller file at the same quality.
Privacy & security
The trim runs entirely in ffmpeg.wasm inside your browser. The source video is never uploaded, logged, or stored. Engine artefacts are served from our own origin (not a third-party CDN).
Related tools
- Video Compressor
Shrink mp4, webm, and mov videos right in your browser with ffmpeg.wasm. Choose a target preset (web 720p / 1080p, Discord 25 MB, Twitter 512 MB) or set a custom H.264 CRF: your files never leave the device.
Video Tools
- Video to GIF Converter
Turn any mp4, webm, mov, or mkv into a high-quality animated GIF: fully in your browser via ffmpeg.wasm. Pick a time range, FPS, width, and dither; we generate an optimised palette in a single click.
Video Tools
- Video Format Converter
Convert mp4, webm, mkv, and mov videos to any of those targets: fully in your browser via ffmpeg.wasm. Pick the container; we auto-pair the right H.264 / VP9 / passthrough codec for maximum playback compatibility.
Video Tools
- Video Frame Extractor
Extract still frames from any video as PNG or JPG: every N seconds, every N frames, at a single timestamp, or N evenly-spaced thumbnails. Runs entirely in your browser via ffmpeg.wasm. Downloads as a ZIP.
Video Tools
- XML Formatter & Validator
Pretty-print, minify, and validate XML with configurable indentation, attribute formatting, and well-formedness checks
Developer Tools
- Username Generator
Generate creative, memorable usernames using adjective + noun + number patterns with configurable separator and length
Generators
Frequently Asked Questions
Lossless vs frame-accurate, which should I pick?
Lossless mode (-c copy) finishes in seconds but snaps to the nearest keyframe, so the cut may land a second or two before your slider. Frame-accurate mode re-encodes with H.264 CRF 18 for exact start frame, at the cost of a slower transcode.
Why is the lossless cut slightly off?
mp4 and other modern containers only contain keyframes every 1-2 seconds. -c copy cannot start mid-GOP, so it snaps to the nearest keyframe before your slider. If you need exact timing, switch to frame-accurate mode.
Does the file get uploaded?
No. Trimming runs entirely in your browser through ffmpeg.wasm. The engine artefacts are served from the same origin under /ffmpeg/<version>/.
Can I trim a webm or mkv?
Yes: the tool keeps the source container, so an mkv stays an mkv. Use the Video Format Converter afterwards if you need a different container.
How big a file can I trim?
There is a 250 MB / 5-minute soft cap to protect mobile devices from out-of-memory crashes. Lossless mode is so fast that even ~1 GB clips on desktop usually finish in well under a minute.