AscendLab

Video tools

Video Trimmer

New ffmpeg.wasm tool

Private Video Trimmer

Trim a video locally with start and end controls. The FFmpeg engine is hosted with the site and loads only after you start processing, so the source file stays on your device.

Quick answer

A video trimmer cuts a selected time range from a source video.

This first version is best for short MP4 or WEBM clips under 200MB.

Best inputs for trimming

Use a short source clip

Browser-side FFmpeg uses local memory and CPU, so smaller files finish faster.

Choose a clear time range

Fast trim is quickest, while MP4 or WebM re-encoding is better for exact boundaries.

Free ToolFFmpeg loads only when needed
Video Trimmer
Trim a local video in your browser with no upload. Use fast stream copy or re-encode to MP4/WebM for a more exact clip.

Drop video here or click to upload

MP4 and WEBM are the safest first-version inputs.

Max file size: 200MB

No video uploaded

Trim settings
Choose the start, end, and processing mode before generating the clip.
0:00 - 0:10

Fast trim is quickest for MP4/WebM clips. Re-encoding is slower but better when you need more exact boundaries.

Keeps the original streams. Faster, but the cut may align to a nearby keyframe.

Not usedLower = higher quality

Clip length

0:10

Engine

ffmpeg.wasm

Output

Original container

Ready0%
Trimmed clip
Review the output size, processing mode, and download the local result.

Output size

No trimmed clip yet

Range

0:00 - 0:10

Mode

Fast trim

Upload a video, choose a range, and trim it to preview the output here.

The video stays on your device. FFmpeg runs inside the browser after you start trimming, so the initial page stays light and the large WebAssembly engine is not loaded until needed.

Example
Upload a 120MB MP4, set the start time to 12 seconds and the end time to 42 seconds, then use fast trim to export a short clip without re-encoding.
Assumption
The browser has enough memory to load the source video and ffmpeg.wasm. Smaller files are more reliable on mobile devices.
Limitation
Browser-side FFmpeg is not a replacement for desktop editing software for very large videos, long exports, batch jobs, or professional color and audio workflows.
Trim mode choices
Pick the mode based on speed, precision, and output format.

Fast trim for quick cuts

Copies streams without re-encoding, which is faster and preserves quality.

MP4 for broad compatibility

Re-encodes the selected range to MP4 with H.264 video and AAC audio.

WebM for browser-native sharing

Re-encodes to WebM when the destination supports modern browser video.

Privacy and performance
The FFmpeg engine runs in your browser after you start trimming.
Source videos are loaded from your device into browser memory rather than uploaded to a backend.
The local FFmpeg WebAssembly file is about 31MB and is lazy-loaded only when needed.
Mobile devices may need shorter clips because video processing is CPU and memory intensive.

Suggested workflow

Build a browser-side video prep workflow

Inspect the clip, trim the useful range, then extract or optimize the visual assets that support publishing.

Step 1
Inspect video
Read duration and dimensions before choosing the range.
Open tool
Step 2
Trim video
Cut a local source video to the selected range.
Open tool
Step 3
Compress or convert
Reduce size or export MP4/WebM for the destination.
Open tool
Step 4
Extract thumbnail
Capture a still frame for a cover or preview image.
Open tool

Related tools

Continue the video workflow

Video Info Inspector
Check duration and dimensions before selecting a trim range.
Open tool
Video Compressor
Reduce the output size after cutting a shorter clip.
Open tool
Video Format Converter
Convert the trimmed result to MP4 or WebM.
Open tool
Video Thumbnail Extractor
Capture a still frame from the source video or the trimmed result.
Open tool
Video to GIF Converter
Turn a short trimmed range into an animated GIF.
Open tool
Frequently asked questions

Does this video trimmer upload my file?

No. The selected video is processed in your browser with ffmpeg.wasm. The current tool does not send the video to a backend.

What is fast trim?

Fast trim copies the original streams without re-encoding. It is quicker and preserves quality, but the cut may align to a nearby keyframe.

When should I use accurate MP4 or WebM?

Use accurate re-encoding when you need cleaner start and end points or a predictable MP4 or WebM output. It is slower and uses more browser memory.

What file size should I use?

The first browser-side version accepts videos up to 200MB. Smaller clips are recommended on mobile devices because ffmpeg.wasm uses local memory and CPU.

Is this the same as video compression or conversion?

No. This page focuses on cutting a clip from a video. Compression and format conversion are separate workflows because they need different quality, bitrate, and size controls.