Reminds me of https://bramp.github.io/js-sequence-diagrams/ The nice thing about that library is that you actually can have a self-contained HTML page with a diagram, like:

    <html>

    <script src="https://cdnjs.cloudflare.com/ajax/libs/webfont/1.6.28/webfontloader.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/raphael/2.3.0/raphael.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.5.2/underscore-min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/js-sequence-diagrams/1.0.6/sequence-diagram-min.js"></script>
    <body>
      <div id="diagram"></div>
    <script>
      var diagram = Diagram.parse("A->B: Message");
      diagram.drawSVG("diagram", {theme: 'hand'});
    </script>

    </body>
    </html>

And this will draw render a sequence diagram in any browser. I've used this to have as documentation in the /docs folder of project Git repository for some of my teams. It is great because it is pretty easy to update and maintain changes via VCS.