How to Annotate a Screenshot on Mac (Arrows, Text, Blur)

An arrow and a few words turn a screenshot into an explanation. Here's how to annotate screenshots on a Mac, with what's built in and with a faster workflow.

With macOS Markup

1. Take a screenshot with ⌘⇧4.
2. Click the thumbnail that appears in the bottom-right corner before it disappears.
3. Use the Markup toolbar: sketch, shapes (including arrows), text, and highlight.
4. Click Done to save, or drag the result into another app.

If the thumbnail is gone, open the file in Preview and choose Tools → Annotate.

Markup works, but it's a detour: capture, then open, then annotate, then export. Shapes become pixels once you save, and there's no blur or pixelate tool. To hide something, you cover it with a filled rectangle.

With Snapok: annotate before you copy

In Snapok the annotation tools appear on the capture overlay as soon as you select a region, so there's no second app.

1. Press ⌃⌘A and select a region.
2. Pick a tool by its key:
   • R rectangle, O ellipse, A arrow
   • P pen, T text, M mosaic
   • V to select and move annotations
3. Change size with 1 / 2 / 3, or [ and ] to step.
4. ⌘Z undoes; Delete removes the selected annotation.
5. Press ⌘C to copy or ⌘S to save, at the original resolution.

Need more room? Press ⌘E to open the full editor, where you can zoom (pinch, or ⌘+ / ⌘−), style text with a font, size, and bold, and add a background and shadow.

Annotations stay editable

Snapok saves annotations as objects alongside the image in your screenshot library. Double-click an old screenshot and you can move an arrow or fix a typo, days later.

Blur in one click

Pixelate any area with the mosaic tool, or let Snapok find and redact emails, phone numbers, ID numbers, and keys automatically, on your Mac.

Tips for clearer annotations

• One idea per screenshot. Crop tight to the thing you're explaining; element snapping makes this easy.
• Arrows point, boxes frame. Use one or the other, not both on the same thing.
• Keep sizes consistent across a set of screenshots, especially in documentation.

Snapok is free and open source. Coming from Snagit or CleanShot X? See how they compare.