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How to Redact or Blur Sensitive Info in Screenshots on Mac

Redact or blur a Mac screenshot: Markup and Preview steps for macOS 26 and 27, why blur can be undone, and how to black out text safely before you share.

6 min readUpdated
BaziFounder & maker of Pizazoo

To redact a screenshot on a Mac with the built-in tools, click the floating thumbnail right after you take it (or open the file in Preview and show the Markup toolbar), draw a rectangle from Shapes, and set both its border and fill color to black. That works the same in macOS Tahoe 26 and macOS 27. Markup has no blur or pixelate tool, and Preview's Redact tool works only on PDFs, so blurring needs another app, and for real secrets you should not blur at all.

Screenshots leak more than people realise. Email addresses in browser tabs. Account IDs in URLs. Credit card numbers on receipts. Faces in Slack avatars. Personal addresses in delivery confirmations. Most of this gets shared with no second thought.

Here's how to redact it properly on Mac.

How do I redact a screenshot on Mac without an app?

Use Markup, which is built into the screenshot thumbnail, Preview and Quick Look. These steps match Apple's guides for macOS Tahoe 26 and macOS 27:

  • Take the screenshot, then click the thumbnail in the corner of the screen to open a window where you can mark it up (Apple). If the thumbnail is gone, double-click the file to open it in Preview and click the Show Markup Toolbar button (Apple).
  • Click Shapes, choose the rectangle, and drag it over the text you want to hide. Resize it with the blue handles.
  • Click Border Color and choose black, then click Fill Color, which changes "the color that's used inside a shape," and choose black (Apple: Mark up files on Mac).
  • Repeat for every name, number, token and face, then click Done (or save the file in Preview).
  • Zoom in before you share it and check that no edge of a letter shows around a box.

Apple notes that "if you annotate an image file, you can't edit, move, or delete the annotations after you save the image," so once saved, the box is part of the picture. Preview can still restore earlier versions of a file you edited (File > Revert To > Browse All Versions), so if other people use your Mac, redact a duplicate rather than the original (Apple).

Can you redact a screenshot in Preview?

Not with the Redact tool. Preview's Redaction Selection tool appears in Apple's guide to annotating PDFs, where it lets you "select text to remove it from view," and the redaction becomes permanent once you close the document (Apple). You can also reach it with Tools > Redact when a PDF is open (Intego). Apple's guide for annotating images lists no redact, blur or pixelate tool, so for a PNG or HEIF screenshot, the filled rectangle above is the Preview method.

One Apple tip to ignore here: to keep annotations editable, Apple suggests converting an image to a PDF and annotating that. That is the opposite of what you want for redaction. In a PDF, a drawn box stays a separate annotation that can still be moved, so redact the image itself and share it as an image.

How do I blur a screenshot on Mac?

macOS has no blur tool for screenshots. Apple's macOS 27 guides for Markup and Preview cover shapes, text, signatures, color, size, rotation and cropping, but not blur or pixelate. Your options:

  • Photos Clean Up, for faces only. Import the screenshot into Photos, double-click it, click Edit, then choose Clean Up (in macOS 27 it is under Tools). Apple says "if you brush over a person's face, the face may become blurred with a pixelated effect" (Apple). It needs Apple Intelligence on a Mac with M1 or later (Apple), and it is not meant for text.
  • Our free browser tool. The Screenshot Redactor can black out, pixelate or blur regions, has an experimental auto-detect for emails, phone numbers and long tokens, and runs in your browser without uploading the image. Disclosure: we make this free tool and Pizazoo.
  • A screenshot app with blur and pixelate tools, such as Pizazoo (below).

Before you blur anything, read the next section.

Is it safe to blur a screenshot, or should you black it out?

Black it out. Blur and pixelate can be reversed by modern image-recovery tools, so if something is genuinely sensitive (credentials, card numbers, full PII), use a solid block, not blur.

  • Security firm Bishop Fox says "the only way to do it securely is to use black bars," and published a tool, Unredacter, that turns pixelated text back into readable text (Bishop Fox).
  • Translucent marks are no better. Highlighter and marker ink is partly transparent, and brightness and contrast edits can bring the text back; a shape at 100% opacity that fully covers the text cannot be seen through (TapSmart). The article is about iPhone Markup, but the same applies on a Mac: use a filled shape, not a pen, highlighter or the Highlight shape.
  • Make the box a little larger than the text, so it does not give away the exact length of a short number or name.

Blur is fine for things that are only distracting (a busy background, a stranger in the corner of a photo). For anything you would not post publicly, use black. Our guide to whether blurred screenshots can be unblurred explains how the recovery tools work.

What else can give away a redacted screenshot?

  • The original file. If you redacted a copy, the unredacted screenshot is still in your screenshots folder (the Desktop by default, which syncs to iCloud Drive if Desktop & Documents is on). Delete it if you don't need it.
  • Metadata. Screenshots carry far less metadata than photos, usually a date, size, color profile and a "Screenshot" label with no location, and covering pixels doesn't change it. See do screenshots have metadata?
  • The rest of the screen. Notification banners, other browser tabs, the address bar, the menu bar clock and avatars all leak context. Crop or cover them too.
  • Work screenshots. For tickets and support threads, our bug report screenshot guide covers what to hide (tokens, cookies, customer data) and how to share safely.

Step-by-step: redact a screenshot in Pizazoo

Disclosure: we make Pizazoo. Pizazoo for Mac (macOS 14 Sonoma or later) is a screenshot organizer: it does not take screenshots, but imports them from the folders where they land. Its markup editor adds the tools macOS lacks: Blur, Pixelate, a solid Black bar, and auto-redaction. See the redact feature page for an overview.

Step 1: Open the screenshot in Pizazoo

Find the screenshot in your Pizazoo library, press Return or Space to open the preview, then click Edit. The markup editor works non-destructively, so the original is preserved.

Step 2: Pick the Redact tool

Click Redact in the toolbar and choose Black bar (solid), Blur or Pixelate. For secrets, choose Black bar.

For automatic coverage, open the AI tools menu in the toolbar, tick the Auto-Redact Targets you want (PII, All Text, Faces, People), set Redaction Style to Solid Redact, then click Run Auto-Redact. The style starts on Blur, so switch it before you run if the screenshot holds anything secret. Detection uses Apple Vision text recognition and pattern matching, all on-device. Blur QR Codes is in the same menu.

Step 3: Drag over the sensitive region

Drag a rectangle across the area you want to hide. In the editor, each redaction stays a separate layer that you can resize or delete. Review what auto-redact found and box out anything it missed, such as names and short account numbers.

Step 4: Save or share

Click Done to apply it. The saved image has the redacted area replaced, while Pizazoo keeps the pristine original in its library on your Mac, so you can reopen the editor later and change or remove the redaction. To keep both versions, open the Done menu and choose Save a copy. Use Share to send it via Mail, Messages, or any macOS share target.

Pizazoo edits its own copy of the screenshot. The original in your screenshots folder stays as it was, unless you turned on Delete originals after import in Settings > Capture, so share from Pizazoo and delete the original if you don't need it.

What Pizazoo redacts automatically

With the PII target (on by default), Run Auto-Redact looks for:

  • Email addresses
  • Phone numbers (most international formats)
  • Credit-card-shaped digit strings (13 to 19 digits)
  • IP addresses (IPv4 and IPv6)
  • API keys and tokens: AWS access keys, JWTs, GitHub and Slack tokens, and keys with known prefixes from services such as Stripe, OpenAI, Anthropic, Google, GitLab, npm, Hugging Face, Shopify, SendGrid and Cloudflare
  • Long strings of letters and digits (32 characters or more) that look like secrets or IDs

Turn on All Text to cover every line of text, or Faces and People to cover people. QR codes are handled by Blur QR Codes; if a code grants access (a boarding pass, a login), draw a Black bar over it as well. For everything else (names, short account IDs), use a manual redact.

Privacy: does Pizazoo upload anything?

No. Redaction and detection run on your Mac with Apple's on-device Vision framework. No image, no text, no metadata is uploaded. The only time your library leaves the Mac is if you turn on iCloud Sync (Pro, off by default), which uses your own private iCloud, with no Pizazoo server.

The redaction tools arrived with the markup editor in Pizazoo 1.0.2 and are part of the free tier. Download Pizazoo free.

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