Free · No upload · No sign-up
Compress Video Online
Shrink MP4, MOV, WebM, and MKV up to 80% — all inside your browser. Your file never leaves your device.
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Drop your video here
MP4, MOV, WebM, MKV — up to 4GB. Processed in your browser.
Why this tool
Nothing leaves your device
All encoding happens in your browser via ffmpeg.wasm. No upload, no retention, no analytics on your media.
Fast on modern machines
Multi-threaded WebAssembly (SharedArrayBuffer) squeezes serious performance out of Chrome, Edge, Firefox, and Safari 16.4+.
Clean output
MP4 (H.264 + AAC), +faststart for instant streaming, yuv420p for universal playback. No watermark, no metadata trail.
How to compress a video
- 1Drop your video into the uploader above (MP4, MOV, WebM, MKV up to 4GB).
- 2Pick a quality preset. Balanced is the sweet spot for most cases; Small for email / chat; High if you will re-edit.
- 3Click "Compress video" and watch the progress bar. Everything runs in your browser.
- 4Download the compressed MP4 when finished. Your original file is not modified.
Frequently asked questions
- Does Clapr upload my video to a server?
- No. Clapr compresses video entirely in your browser using WebAssembly. Your file never leaves your device, so there is no upload, no account needed, and no waiting in a queue.
- What formats are supported?
- Most common formats decode in-browser: MP4, MOV, WebM, MKV, M4V, AVI, and others ffmpeg supports. The output is always MP4 (H.264 + AAC) for maximum player compatibility.
- How small will my file get?
- Typical savings are 50%–80% depending on the preset. "Small" targets ~1 Mbps (email / chat size), "Balanced" ~2 Mbps (default, barely perceptible quality loss), "High" keeps most of the original quality while shaving a modest amount.
- Why does it feel slow on my phone?
- In-browser video compression is CPU-heavy. On mobile we recommend files under 200MB. Very large files or older phones may fall back to our server processing (coming soon) for reliability.
- Is there a watermark?
- No watermark. Ever. The compressed file is a clean MP4, same aspect ratio, ready to upload anywhere.
- Is there a file size limit?
- Up to 4GB per file in the browser. Bigger files need enough free memory — typically 2–3× the file size — so performance varies by device.
- What about audio-only?
- The compressed output always has audio (re-encoded to AAC). If your source is silent, the output keeps the silent track. For audio-only extraction, use our Extract Audio tool.
- Is Clapr really free?
- Yes — compress video is free with no account. Clapr has paid tiers for high-volume transcription and large server-side jobs, but in-browser compression is always free.