Which formats are supported?

Read: MP4, MOV, MKV, WebM, AVI, FLV, 3GP, MTS, and more. Write: MP4 (H.264/H.265), WebM (VP9/AV1), MOV, GIF, MP3, WAV, FLAC, Opus, AAC.

Is there a file size limit?

Only your device's available memory. WebAssembly caps at 2–4 GB per file. Most laptops handle 1080p videos under a gigabyte comfortably; multi-gigabyte 4K is better handled with a desktop tool.

How fast is the conversion?

For common formats (MP4, WebM, MOV) we use WebCodecs for hardware-accelerated speed — often faster than real-time on modern devices. For exotic formats we fall back to FFmpeg-WASM, which is 10–20× slower than native FFmpeg but still works in your browser.

Convert video — right in your browser

Drop in a .mov, .mkv, .webm, .avi — or whatever you've got. Convert, compress, trim, extract audio, make a GIF. Nothing uploads. No signup, no watermarks, no quotas.

100% client-side FFmpeg + WebCodecs No upload Works offline

//Tools

Convert format

MP4, MOV, MKV, WebM, AVI, GIF, MP3, WAV, FLAC, Opus — pick input, pick output.

Compress video

Smaller file, same video. Target a bitrate or pick a quality level.

Trim clip

Cut the start, cut the end. Lossless when possible, accurate when not.

Extract audio

Pull the soundtrack out as MP3, WAV, FLAC, or Opus.

Extract frames

One frame per second, every frame, or grab a single thumbnail at a timestamp.

Video to GIF

Make a clean, palette-optimized GIF from any clip.

Merge clips

Concatenate two or more videos into one. Same format goes fast; mixed formats re-encode.

Resize

1080p, 720p, 480p, or a custom size. Keep aspect ratio or stretch.

Rotate & flip

Fix sideways phone videos. 90°, 180°, mirror horizontally or vertically.

Change speed

Slow-motion or speed-up. Audio retunes with the video.

Burn subtitles

Hard-code an .srt file into the video so it plays anywhere.

Mute / strip audio

Remove the soundtrack and re-export.

//Format-specific

MOV → MP4

The iPhone-to-everything-else conversion.

MKV → MP4

Open MKV anywhere — including phones.

WebM → MP4

Twitter, Discord, and Premiere-friendly.

AVI → MP4

Modernize an old AVI file in one click.

MP4 → MP3

Pull just the audio out of any video.

MP4 → GIF

Make a shareable GIF without uploading.

//Why ShrinkVideo?

No uploads, ever

Your video is read by WebAssembly and WebCodecs inside your browser. The bytes never leave the tab.

Offline-capable

Load the page once, then disconnect. Every tool keeps working.

No limits

No quotas, no daily caps, no signup, no waiting in a queue. Only your RAM matters.

Fast where it counts

WebCodecs runs hardware-accelerated for common formats — often faster than real-time. FFmpeg-WASM picks up everything else.

//FAQ

Do my videos actually stay on my device?

Yes. Every operation runs in JavaScript and WebAssembly inside your browser. You can verify by opening the page, pulling the network plug, and trying any tool — it still works.

Which formats does ShrinkVideo support?

Read: MP4, MOV, MKV, WebM, AVI, FLV, 3GP, MTS, M2TS, OGV. Write: MP4 (H.264, H.265), WebM (VP9, AV1), MOV, GIF, and audio-only outputs in MP3, WAV, FLAC, Opus, AAC.

How big a video can I convert?

Roughly your tab's available memory. WebAssembly is capped at 2–4 GB per file. Most 1080p videos under a gigabyte work fine on a laptop. Multi-gigabyte 4K should use a desktop FFmpeg.

Is there a watermark?

No. No watermark, no signup, no “upgrade to remove” nag.

How fast is it?

For common formats (MP4 in/out, WebM, MOV) we use WebCodecs — hardware-accelerated, usually faster than real-time. For exotic formats (MKV with AC3, ProRes, etc.) we use FFmpeg-WASM, which is 10–20× slower than native FFmpeg but still gets the job done in your browser.

Why is it free?

The site is supported by unobtrusive ads. There's no server doing the conversion, so running it is mostly the cost of static hosting.

Does it work on mobile?

Yes. Browsers on modern iOS, iPadOS, and Android all support WebCodecs and WebAssembly. Conversion is slower on phones because the CPU is slower — that's not us.