How to Blur Sensitive Information in a Screenshot on Mac

Screenshots leak things: an email address in a sidebar, a customer's phone number in a table, an API key in a terminal. Here's how to hide them on a Mac before you share.

Blur vs. cover: what's actually safe

Light blurs can sometimes be reversed or guessed, especially on short text like numbers. Safer options replace the pixels: a solid box or a strong mosaic. Whatever you use, make sure you share a flattened image, not an editable file with the original underneath.

With Preview (built in)

Preview doesn't have a blur tool, but you can cover text:

1. Open the screenshot in Preview and choose Tools → Annotate → Rectangle.
2. Draw a box over the sensitive text.
3. In the shape style, set a solid fill color.
4. Choose File → Export to save a flattened copy.

It works, but it's manual, and it's easy to miss one email in a long screenshot.

With Snapok: automatic, on-device redaction

Snapok finds common sensitive patterns for you, using Vision text recognition and pattern matching on your Mac.

1. Capture with ⌃⌘A, then press ⌘E to open the editor.
2. Choose AI Tools → Redact Sensitive Information.
3. Snapok covers email addresses, phone numbers, ID numbers, and keys it finds.
4. Review. Undo any you don't need, or press M and drag to pixelate anything it missed.
5. Copy or save. Exports are flattened, so the originals are gone.

No API key is needed and the unredacted image never leaves your Mac.

Built for sharing safely with AI, too

If you later use Snapok's Ask or translation features with your own model, the image sent includes your current annotations, so redacted areas stay redacted.

A quick checklist before you share

• Names, emails, and avatars in sidebars and headers.
• Tokens and keys in terminals, .env files, and URLs.
• Customer data in tables and dashboards.
• Browser tabs and bookmarks bar.

For a whole page, take a scrolling screenshot and redact it in one pass. Developers and technical writers use this daily.

Snapok is free and open source. Xnapper also auto-redacts; here's how they compare.