About the Privacy Blur Tool

What it does

Lets you blur, black out, or erase sensitive areas in any image directly in your browser — no upload to a server required. Everything is processed locally on your device.

How to use it

Drop or select an image, then use the Blur, Black, or Erase tools to paint over any area you want to redact. Adjust the brush size as needed, then save the result.

Blur — applies a mosaic blur to the painted area, obscuring detail
Black — fills the painted area with solid black, fully hiding the content
Erase — removes any previously applied effect from the painted area
Save — downloads the modified image as a PNG file

What gets blurred and why

Privacy blur tools are used before sharing screenshots containing sensitive information: API keys, passwords, email addresses, personal details, financial figures, and internal URLs. Blurring is preferable to cropping because it preserves the context and layout of the screenshot while obscuring specific values, making the image more useful to the recipient.

Screenshots for documentation — blur credentials and personal data before adding to wikis or tickets
Social media posts — blur account numbers, addresses, and names before sharing publicly
Bug reports — share full-context screenshots without exposing production data
Client presentations — redact pricing, user volumes, or internal metrics as needed

GDPR and screenshot sharing

Under GDPR, sharing screenshots containing personal data (names, email addresses, account numbers, IP addresses) constitutes processing of personal data. This is particularly relevant when sharing screenshots in bug reports, Slack channels, support tickets, or public documentation. Blurring or redacting personal data before sharing reduces GDPR compliance risk.

Bug reports — redact any user data visible in the screenshot; use test accounts for screenshots where possible
Support tickets — customer names, emails, and order numbers should be blurred when sharing with third-party vendors
Documentation — public-facing docs should never contain real user data; use synthetic data or anonymised screenshots
Team communication — internal sharing in Slack or Teams is still subject to GDPR if personal data is visible

Frequently Asked Questions

Is my image uploaded to a server?

No. Privacy Blur uses the HTML5 Canvas API to process images entirely within your browser. Your image data never leaves your device.

What is the difference between Blur and Black box?

Blur applies a pixelated mosaic effect that obscures content while keeping the general shape visible. Black box replaces the area with solid black, which is stronger and used in formal document redaction.

Can I undo a stroke?

Yes. Click "Undo last" to revert the most recent brush stroke. Multiple undos are supported.

How do I blur part of an image on a Mac?

Use Preview: open the image, select the area with the selection tool, then go to Tools > Annotate > Redact (macOS Monterey+). On older versions, use the highlight tool with a black fill. Alternatively, open in Keynote, add a shape with black fill over the sensitive area, then export as an image.

What tools can I use to redact PDFs?

Adobe Acrobat's Redact tool permanently removes and blacks out text and images. ilovepdf.com offers online PDF redaction. Preview on macOS can draw black shapes over content but the underlying text may still be selectable; always use a proper redaction tool for sensitive documents rather than covering with shapes.