Free Online Screen Recorder
A Screen Recorder That Can't Leak Your Recordings
Most "online" screen recorders are cloud pipelines: your screen is uploaded first, stored somewhere, then handed back to you as a link. CastLens inverts that. Recording happens inside your browser tab, the file is written straight to your disk, and there is no server on the other end — because the site doesn't have one.
Open CastLens and record nowWhy screen recordings leak
When a recorder uploads, three things can go wrong: the transfer itself (who sees it in transit), the storage (how long it sits there, who can read it), and access control (link guessing, sharing settings, breached accounts). Sensitive demos, unreleased products, customer data on screen — one mis-shared link and it's out. The only reliable fix is to never send the video anywhere in the first place.
How browser-local recording works
Modern browsers expose two standard APIs: getDisplayMedia() captures the screen into a live stream inside the page, and MediaRecorder encodes that stream in memory. When you press Download, the finished blob is written to a file. Between those steps there is no network hop — the video never becomes a request.
A 60-second trust test for any recorder
Before recording anything sensitive, open DevTools → Network, hit Record, and watch. A local recorder shows zero requests after page load. Then check the tool's privacy policy for words like "processing", "retention", and "improve our services" — each one means your video goes somewhere you don't control.
When private recording is the requirement
Internal demos of unreleased features, bug reports containing user data, financial screens, medical or legal workflows, security-sensitive admin panels, and any company bound by NDAs or GDPR-style rules. If the content would be a problem in someone else's cloud, it should never touch a cloud.
FAQ
Does CastLens really never upload anything?
Yes — it is a static page with no backend. The recording is produced and encoded inside your browser and saved directly by you. You can verify this with the browser's Network panel while recording.
Can my employer or network admin see my recordings?
Not through CastLens — there is nothing to intercept because nothing is transmitted. What happens on a managed device is governed by your device policy (screen monitoring, disk encryption), which applies equally to any installed app.
Does it work offline?
Yes, after the page has loaded once. Recording, pausing, stopping, and saving all work with the network disconnected — which is itself proof that nothing is being uploaded.
What happens to the video when I close the tab?
It's gone. The unsaved recording exists only in the tab's memory. Unless you pressed Download, no copy exists anywhere — on this site or any other.
Is a browser recorder as private as an installed app?
For recording privacy, yes — both capture and encode locally. An installed app additionally works without loading a website first; a browser tool has the advantage of zero install and nothing left on the machine afterwards. Pick based on workflow, not privacy.