OVERLAID

// GUIDE · UPDATED OCTOBER 2026

Open source screen annotation tools for Mac

THE SHORT ANSWER

The main open source options are ZoomIt for Mac, DrawPen, Annotate and KeyCastr. Overlaid isn't open source, but you can try every feature free for 7 days.

If you'd rather run something you can read the code for, there are good open-source options for the Mac.

All four here install with one Homebrew command.

METHOD 01

ZoomIt for Mac

MIT, by Microsoft Sysinternals

Zoom, live zoom, draw on the zoomed frame, snips with on-device OCR, screen recording and a break timer.

  1. 1brew install --cask zoomit

GOOD

  • +Backed by Microsoft
  • +Very full-featured

NOT SO GOOD

  • −Draws on a frozen capture
ZoomIt for Mac on GitHub ↗

METHOD 02

DrawPen

MIT

Pen, shapes, text, highlighter, laser, eraser and a whiteboard. Runs on macOS, Windows and Linux.

  1. 1brew install --cask drawpen

GOOD

  • +Cross-platform
  • +Popular on GitHub

NOT SO GOOD

  • −Not a native Mac app
DrawPen on GitHub ↗

METHOD 03

Annotate

MIT

A native Mac app with fade and persist modes, a board mode, cursor spotlight, counters and a floating toolbar.

  1. 1brew install --cask annotate

GOOD

  • +Native Mac app
  • +Updates itself with Sparkle

NOT SO GOOD

  • −Needs macOS 14 or later
Annotate on GitHub ↗

METHOD 04

KeyCastr

Open source

Keystrokes only, the long-standing open-source keystroke visualiser for macOS.

  1. 1brew install --cask keycastr

GOOD

  • +Free, extensible

NOT SO GOOD

  • −No drawing
KeyCastr on GitHub ↗

METHOD 05THAT'S US

Overlaid (closed source)

$11.99 once, 7-day free trial

Not open source. We list it because it combines what these do separately: drawing, zoom, cursor effects and keystrokes. It draws everything in memory and never uploads anything.

  1. 1Download the 7-day trial.

GOOD

  • +Everything in one app
  • +No account, no telemetry

NOT SO GOOD

  • −Closed source
  • −Paid after the trial
Try Overlaid free for 7 days →

// WORTH KNOWING

THREE TIPS.

Check activity

Look at recent commits and releases. Screen capture APIs change with macOS updates.

Read the permissions

Drawing needs no special permissions. Zoom and snips need Screen Recording. Keystrokes need Accessibility.

Star what you use

Open-source tools live on attention. If one helps you, star it or send a fix.

// FAQ

QUICK QUESTIONS.

Yes. Annotate and DrawPen are both MIT licensed, and ZoomIt for Mac covers zoom and drawing.

No. It's a paid app with a free trial. It doesn't record, store or upload anything.

// COMPARE

// GUIDES

// ALSO FOR

// YOUR NEXT CALL

Draw on your screen in the next five minutes.

7 days free with every feature. Then a one-time purchase. No account, no subscription.

BUY OVERLAID · $4.99or try it free for 7 days