The first forty seconds of every screen recording is you finding the stop button from last time. Trimming an MP4 down to the part that matters shouldn't mean uploading a possibly-private recording to a random site.
Load the file, set in and out points on the player, and export. Your browser decodes the MP4 (H.264 MP4s play basically everywhere) and re-encodes just the selected range locally, in real time, with the duration verified afterwards.
Loading tool…
This is Trim Video preconfigured for this task — open the full tool for every option.
Select a video; it loads into a local player.
Set start and end points with the range controls or by seeking.
Export — the selected range plays through a local capture pipeline and is re-encoded in real time.
The output is re-opened to verify its duration is within tolerance, then downloads.
The exported clip is loaded into a local decoder and its duration is compared with your selected range within a stated tolerance; a mismatch marks the output Failed verification.
The tool uses the encoder built into your browser, which outputs WebM. That keeps everything local with no big engine download. If a destination strictly demands MP4, most editors and even VLC convert WebM in seconds.
Practically yes: the export replays your exact selection and the result is verified against it within a small tolerance, which for screen recordings and clips is indistinguishable from frame-exact.
Technical guidance for choosing settings and reviewing the result.
Video compression is a set of measurable tradeoffs, not a mystery slider. Here is what actually changes file size, how to estimate the result, and which setting to adjust first.
8 min read · Reviewed August 2026