Compress Video Online

Make large video files easier to share

Video files can become huge when they are recorded at high resolution, high bitrate or long duration. That makes them difficult to email, upload to a form, attach to a support ticket or store alongside a project. This video compressor re-encodes your file as an MP4 using controls that matter most: CRF quality and optional width scaling. The goal is to reduce size while keeping the result good enough for sharing, review or web publishing.

Unlike upload-based compressors, this page runs entirely in your browser. ffmpeg.wasm reads the selected file, encodes a new version in an in-memory workspace and downloads the result. Your original video never leaves your device. That privacy-first model is valuable for client work, unpublished product footage, internal training materials, personal clips or any recording that should not be copied to an unknown server.

Balancing CRF and resolution

CRF controls visual quality. Lower values such as 18 to 22 preserve more detail but create larger files. Higher values such as 28 to 32 shrink more aggressively and may show softness or blockiness, especially in motion. Width scaling reduces the number of pixels in every frame. A 4K recording scaled to 1280 pixels wide can become dramatically smaller and is often still clear enough for a web preview or screen recording demonstration.

Browser performance expectations

Compression is the heaviest tool on Media Tools because it decodes and re-encodes video frames. The first run also downloads the WebAssembly engine. Keep the page open and avoid starting other demanding tasks while encoding. If a conversion fails or your device runs low on memory, try a shorter clip, a smaller width or a less aggressive CRF. Always compare the downloaded file with the original before replacing important media.

Settings behind the result

The output is always H.264 video with AAC audio at 128 kbps, encoded with the veryfast preset. That preset favors speed in a browser; a slower preset could squeeze out a little more size reduction, but it would take far longer with WebAssembly. The CRF slider ranges from 18 to 35, and the default of 26 is a reasonable starting point for web sharing.

The width limit only ever shrinks a video: a clip narrower than your value keeps its own width, and the height follows automatically to keep the aspect ratio. Set the width to 0 to keep the original dimensions and rely on CRF alone. A practical approach is to try CRF 26 with 1280 pixels first; if the file is still too big, raise CRF by two or three steps, and if faces or text look rough, lower it again. Compression also cannot help much with footage that is already heavily compressed, so a small input may even grow slightly.