VidSlim

Compress Video Online — Private, Free, No Upload

Shrink any video under a target file size, entirely in your browser. Powered by FFmpeg WebAssembly — your file never leaves your device. No watermark, no sign-up, no file-size tricks.

Popular workflows

Compress for a specific platform

Compress to a target size

Compress by type & quality

Why in-browser compression is different

Most online video compressors upload your file to a server, process it there, and make you download the result. That means waiting through two large transfers and trusting a third party with your footage. This tool runs FFmpeg — the same engine professionals use — compiled to WebAssembly inside your browser. Nothing is uploaded, there is no queue, and confidential videos stay on your machine.

How target-size compression works

Enter a target size and the tool computes a video bitrate budget from your clip's duration: total bit budget = size ÷ length, minus a fixed audio allocation and container overhead. The encoder aims below that budget and can retry with a corrected bitrate if the first output is still too large.

Need a private workflow?

Read the step-by-step guide on how to compress a video without uploading it, or turn a short clip into a shareable loop with the private video to GIF converter, or browse all VidSlim guides.