About this browser-based video editor
A small, free tool that cuts, speeds up and slows down video without uploading it anywhere. Here is who runs it, why it exists, and what it does with the little data it does see.
Who operates alter.video
The site is built and run by Kyllian, a developer working under the GitHub handle InstantlyMoist. It is a personal project, not a company, and there is no team behind it. That GitHub profile is also the way to reach me about a bug, a broken file or anything on this site.
Why it exists
Trimming twenty seconds off the front of a screen recording is a thirty-second job, and the usual options make it a five-minute one. Installing a desktop editor is heavy-handed for a single cut. The free web editors want the whole file uploaded first, then an account, and then they stamp a watermark on the way out.
Browsers can now do the work themselves. FFmpeg compiled to WebAssembly decodes, filters and re-encodes video at a speed that is perfectly reasonable for a clip a few minutes long, and it does it inside the page. Once that is true, uploading is simply an unnecessary step — so this editor does not have one. Three operations, one timeline, no account, no watermark. The technical write-up covers the mechanism in detail.
How it is paid for
It is not, really. The site is a static build served from a small container: a domain, a bit of bandwidth and no per-user cost, because your machine does the encoding rather than a server the site would have to rent. There are no ads, no paid tier, no upsell and nothing to buy. If the traffic ever outgrew that, the honest options would be a donation link or a sponsor — not a watermark and not a sign-up wall.
What the site collects — and what it doesn't
Your video is never uploaded. That claim is structural rather than a promise: the application has no upload endpoint, and the file is read, edited and written back entirely inside the browser tab.
The site does, however, run analytics, and it would be dishonest to imply
otherwise. Every page loads P-analytics from
api.panalytics.money,
which records a cookie-less page view: the address of the page, the referring
page, any campaign parameters in the URL, and how long you stayed. Your browser
and country come from the request itself, as they do for any web request. It does
not set cookies, does not follow you across other websites, and has no visibility
into the video you are editing — the editor and the analytics script never
exchange anything.
The privacy page
spells this out in full.
How it is built
A static Astro site with Tailwind CSS, a single React island for the editor itself, and ffmpeg.wasm doing the actual video work — a WebAssembly build of FFmpeg. It is served by Caddy from a Docker container. The source repository is currently private; the tooling it is built on is all open source and linked above.
What it deliberately does not do
- No multi-track timeline, titles, transitions or colour grading — it is a trimmer, not a suite.
- No cloud storage or project saving. Close the tab and the video and your edits are gone; the only thing kept is the output format and resolution you last clicked, in localStorage.
- No account system, so there is nothing to log in to and no credentials to lose.
- No frame interpolation for slow motion; the existing frames are stretched, not invented.
If one of those is what you need, a desktop editor is the right tool. If you just need a section gone, faster or slower, the editor is on the homepage.