Guide
How to blur private detailsin a screenshot on Mac
A screenshot shows everything on your screen, not just the part you meant. Before you send one to a colleague or an AI chat, here's how to hide what shouldn't go with it.
What usually needs hiding
Most leaks are things nobody noticed were on screen. Have a look for these before you share.
- Email addresses and names, in inboxes, sidebars and the corner where you're signed in.
- Card and account numbers on payment pages, invoices and banking screens.
- Passwords, keys and tokens in settings pages, code and terminal windows.
- Customer details, other people's messages, and notifications that popped up at the wrong moment.
- Browser tabs and file paths, which can show your name, your company or what you're working on.
The built-in way
Markup, the editing tool built into your Mac, has no blur. What it can do is cover a detail with a solid box, which works well.
Take the screenshot
Press Shift-Command-4 and drag around what you need. Click the thumbnail that appears in the corner to open Markup. For a saved file, open it in Preview and click the Markup button.
Cover the detail
Click Shapes, choose the rectangle and drag it over the detail. Set Fill Color to solid black, and the border to match, so nothing shows through.
Check, then save
Zoom in to make sure the box covers every letter. Click Done. Send it as a picture, such as PNG or JPEG, not as a PDF.
A few things to avoid
Don't use a highlighter or a see-through colour, as the text can still be read underneath. In a PDF, a box can sit on top of the page and be moved off again, so export to a picture first. And repeat the steps for every detail, because each box is placed by hand.
If you don't need that part of the screen at all, cropping it out is even safer than covering it.
Faster with Hyduri Capture
Hyduri Capture has Auto-Blur built in. One press finds the usual private details and blurs them for you, before the picture goes anywhere.
Click the camera
Your whole screen is captured. Or hover over the camera and choose one screen or window.
Press Auto-Blur
It finds emails, card numbers, passwords and keys, and blurs them. Then have a quick look over the picture, as it can miss things.
Blur the rest
Spotted something it didn't catch, like a name or a customer's message? Choose Blur, which sits beside Select and Crop, and drag over it to blur it yourself.
When it looks right, click in your chat and press Send to Chat. Or use Copy or Share. What you send is the blurred picture.
Send less in the first place
Keep only one part
Choose Crop and drag around the part to keep. Everything outside it is gone. Undo brings the whole picture back if you change your mind.
Send just the marked bits
Mark the parts that matter and press Crop into Tiles. You get one sheet of just those tiles, and that's all that gets sent.
Nothing leaves early
The app uploads nothing. A picture only leaves your Mac when you send, share or paste it.
Good to know
Will Auto-Blur catch everything private?
No tool can promise that. Auto-Blur looks for emails, card numbers, passwords and keys. Names, addresses and anything unusual may need blurring by hand, so always have a quick look before sending.
Does Auto-Blur send my screen anywhere to check it?
No. Nothing is uploaded by the app. Your picture stays on your Mac until you send, share or paste it.
Does it work for pictures from my phone?
Yes. Choose Add from Phone, scan the code and pick photos. Both need to be on the same Wi-Fi. Then blur them like any other picture.
Share the screen, keep the secrets
Hyduri Capture is $29 once for up to two devices, with no subscription. Every feature is free for 7 days. It needs macOS 14 or newer.
More guides: Send a screenshot to ChatGPT · Annotate a screenshot · Record your screen with captions