How to Trim a Video in the Browser — Frame-Accurate, No Upload

To trim a video in the browser, use Zro7 Trim Video. Set start and end timestamps on a visual timeline, choose fast (stream-copy, cuts at the nearest keyframe) or precise (re-encode, frame-accurate), and download. Everything runs via ffmpeg.wasm — no upload, even for GB-scale recordings.

Fast vs precise: pick the right mode

• Fast (stream copy) — copies packets without re-encoding. Instant even on huge files, but the cut snaps to the nearest keyframe (typically every 1–3 seconds). Zero quality loss. Best for rough trims.
• Precise (re-encode) — decodes and re-encodes, so cuts land on the exact requested frame. Slower and reintroduces one generation of encoding. Use when the edit boundary matters (e.g. removing a specific spoken word).

Why keyframes matter

Modern codecs (H.264, H.265, AV1) only encode complete frames (I-frames / keyframes) periodically; frames in between are diffs. You can't cut mid-diff without decoding, which is why fast mode snaps to the nearest keyframe. If your source has sparse keyframes (long GOP), fast-mode cuts can be seconds off — precise mode is required.

Steps

1. Open Trim Video.
2. Drop the source file.
3. Drag the timeline handles or type exact timestamps (00:01:23.400).
4. Pick fast or precise.
5. Click Trim and download.

Common workflows

• Cut a 3-hour meeting recording to the highlight reel; use fast mode.
• Chop the pre-roll off a phone video before posting; precise mode ensures no black frame.
• Extract multiple clips: run the tool once per clip; batch merge later with Merge Videos.