How to black out text in a screenshot offline
You don’t need to upload a screenshot to a website to hide what’s in it. BlotOut is a browser tool that draws solid black over text and bakes it into the exported image — all on your device, and it keeps working without a connection once the page is loaded.
BlotOut — try free, unlock lifetime for $2.99
Solid-black screenshot redaction in your browser. Free: 2 watermarked exports · $2.99 lifetime: unlimited, no watermark.
Steps
- Open BlotOut once while online. Load the BlotOut app. After that, the editor runs locally in the tab.
- Drop your screenshot. PNG, JPG, or WebP. It is decoded in the browser, not sent anywhere.
- Drag black boxes over the text. Cover emails, names, order numbers, tokens, addresses, avatars — whatever shouldn’t be shared.
- Export PNG. The black is burned into the exported pixels. The export is re-encoded, which also drops the original file’s EXIF metadata.
What “offline” means here
BlotOut is a static web page: drawing and exporting use the browser’s Canvas APIs, so there is no server step. The optional auto-detect hints (spotting emails, phone numbers, API keys) use in-browser OCR that needs to load its library over the network — you can skip them and draw boxes by hand fully offline.
Built-in alternatives
- Phone markup tools — iOS and Android editors can draw shapes; use a fully opaque black shape, not a highlighter or pen with transparency.
- Desktop editors — any image editor works if you fill with 100% opaque black and export a flattened PNG/JPG (not a layered file).
- Avoid blur and pixelate for text: see is blurring a screenshot safe?
BlotOut — try free, unlock lifetime for $2.99
Solid-black screenshot redaction in your browser. Free: 2 watermarked exports · $2.99 lifetime: unlimited, no watermark.
FAQ
Is BlotOut free?
Free tier: 2 exports with a small watermark. $2.99 one-time lifetime unlock removes the watermark and the limit.
Does BlotOut upload my image?
No. Editing and export happen in your browser with Canvas; there is no backend.
Can a solid black box be removed later?
Not from the exported file — the original pixels under the box are replaced with black. Keep in mind the original screenshot on your device still has the data.
Which formats are supported?
PNG, JPG, and WebP in; PNG out.
Sibling tools
More guides
- How to redact a PDF without uploading it
- How to black out text in a PDF permanently
- How to hide an email address in a screenshot before sharing
- Is blurring a screenshot safe?
- How to remove EXIF location from an iPhone photo
- Remove GPS from a photo online — without uploading it
- How to remove AI metadata (C2PA) from an image
All tools: GreenTools hub · Compare: BlotOut vs blur · DocBurn vs PDF redact