Mac Sequence Diagram makes it incredibly easy to create UML 2.0 style sequence diagrams, using nothing more than plain text (and a sprinkling of emoji).

It supports :-

• Participants
• Participant Boxes
• Signals
• Nested Interaction Frames
• Nested Activation Boxes
• Found signals
• Lost signals
• Multiple signal arrow line styles
• Multiple signal arrow head styles
• Export PDF
• Export PNG
• Export SVG
• Export via the Command Line
• Syntax Highlighting in Diagram Text Editor
• Error highlighting
• Canvas zoom up to 14x
• Collapsable Diagram Editor
• Light & Dark modes
• Keyword Auto-Completion
• Participant name Auto-Completion
• Version Control Friendly File Format

And so much more.

Feedback, issues and suggestions are welcomed.


What’s New

Version 1.6.1

* Adds support for command line exporting (see Help/Sequence Diagram Help)
* Fixes a crash when modifying an empty document.
* Fixes a defect where Participant Boxes would have the wrong label text colour in exports
* Fixes defect where auto-signal numbers would be excluded from exports
* Fixes an SVG export defect where Interaction Frame guard clauses would have the wrong text colour
* Adds drag and drop support to application window.
* Now exports using default diagram colours (unless intentionally overridden in the document)
* Fixes a defect where syntax colouring could be lost, in large documents
* Improves support for observing changes to the file, when edited externally
* Improves support for CJK(V) character sets

Other recent enhancements
* Fixes a defect where interaction frames could be widened in exports
* Default save location is now the same as the source file's location
* Minor performance improvements when working with large documents
* Now remembers Auto-Complete, Auto-Signal Numbering and Line Number preferences
* Improves element grouping in SVG export
* Adds support for dragging the Diagram Canvas

A massive thank-you for all the feedback and suggestions.

Please keep ‘em coming and don’t forget to rate and/or review.

Thanks again for your valued support.

-- Mike

Ratings and Reviews

4.8 out of 5
68 Ratings

68 Ratings

Big Balagan ,

Does exactly what it does beautifully and clearly

If you want sequence diagrams this is the way to go. Not only can you devise all the basic flows, you do so with a interpreted “compiler” window that processes a set of simple commands/syntax. You might think this is round-about compared to directly manipulating graphical elements, but I find somewhat to my surprise that thinking about sequence construction using the app’s syntax is a much cleaner and more clear approach to design—and the drawing is done automatically and with pretty good aesthetic values too. This is a very unusual example of both perfect fit of execution to the problem space as well as providing enough, but not too much capability and without any missing. When you use a tool like this, the fit is so precise that tool use sort of disappears from your immediate consciousness and you just solve the problem. Tremendously productive, I learned in in about 15 minutes. Very very good work.

Developer Response ,

Thanks for the kind review, Big Balagan; it is greatly appreciated. -- Mike. 🤓

reidnez ,

Great Tool

This app does what I need, was easy to learn, and I've encountered no major bugs or stability issues. You 'write' your diagram in a very simple domain-specific language. Don't let that put you off, there's no real learning curve: it's very easy to copy and adapt from the excellent template provided. Your diagram is then rendered automatically as you go, and you can (of course) export as a PDF and such. It's a novel approach and I love it. If you're someone who appreciates the elegance and efficiency of text-based interfaces, you'll probably like it, too.

BigRedCliff ,

Well designed and easy to use, excellent documentation

If you need this, you will find it very nicely designed, easy to learn to use, continuing to improve, and effective in generating quality sequence diagrams.

The ability to edit text and have the diagram updated (as opposed to drawing the diagram directly) is great in a number of ways.

1) You spend your time concentrating on the content, as opposed to fiddling with appearance, so you get a more effective result.

2) You immediately see how your text description affects your diagram; that immediate feedback helps you to edit your diagram design as you go.

3) The cost of revising your diagram is just copying, pasting and editing sections of text in the editor, which is very low. This encourages refining your design to get a better outcome.

Very nice, kudos to the Developer :-)

Developer Response ,

Thanks for the kind review, BigRedCliff; it is greatly appreciated. -- Mike.


Mike O Abidakun
11.2 MB

OS X 10.11 or later, 64-bit processor



Age Rating
Rated 4+
© Mike O. Abidakun


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.