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About this tool
Hide sensitive areas in a screen recording with timed solid, blur, or pixelated regions, then export a flattened WebM locally.
The Screen Recording Redactor covers sensitive areas of a screen recording with timed rectangles — solid fill, blur or pixelation — and re-encodes the video so the hidden pixels are gone from the file, not just hidden behind an overlay. Each region has its own start and end time, so a password field can be covered for the eight seconds it is visible and left alone after that. Export redraws every frame onto a canvas at the video's native resolution and records it at 30fps through MediaRecorder into a WebM, entirely on your machine.
Open Screen Recording Redactor on AltFTool — it loads instantly in your browser.
Press Select video and load a screen recording — any video/* file your browser can decode; the file stays on this device.
Choose a New region style of Solid cover, Blur or Pixelate, drag over the preview to add a region, then set its Start and End in seconds in the Region inspector.
Press Export redacted WebM, which re-records the canvas in real time, then Download WebM to save your-filename-redacted.webm.
Redaction is baked into every exported frame, so no one can scrub the overlay off the way they can with a video editor's layer or a CSS mask.
Every rectangle carries its own start and end time, so covers appear and disappear with the content instead of blocking the frame for the entire video.
Blur radius is at least 8px and grows with the smaller side of the box, and pixelation downsamples each side of the region to a sixteenth of its length (a 256th of its area) before enlarging it with smoothing off.
Use solid fill for anything that must never be recovered. Blur and pixelation reduce detail but are reconstructions of the original pixels, and text with a known font and layout has been recovered from weak pixelation before — solid fill writes over the area completely.
On most browsers, a WebM saved as your-filename-redacted.webm — it prefers VP9 with Opus audio, falls back to VP8 with Opus and then to whatever plain video/webm the browser offers. Browsers without a WebM MediaRecorder (Safari, for example) record in their own default container instead, and the download's file extension always matches the real container. The canvas is captured at 30fps at the source video's native pixel dimensions either way.
Because the export plays the video through and records the redrawn canvas in real time — a four-minute recording takes about four minutes to write. There is no faster offline encode path in the browser, so leave the tab in the foreground while it runs.
Yes where the browser supports capturing a stream from the video element — the source audio tracks are added to the recording stream alongside the redacted canvas. Support varies by browser, so play the exported file back before deleting the original, and note that redaction is visual only: anything spoken aloud is still in the audio.