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SequenceDiagram.org is an online tool / software for creating UML sequence diagrams. Founded in 2014 with the purpose to improve the efficiency when creating and working with sequence diagrams by combining text notation scripting and drawing by clicking and dragging in the same model.

All parsing, processing, and drawing is done client side. The benefit of this is that SequenceDiagram.org is fast and convenient to work with; it also doesn't transfer your diagram data over the Internet like many other sequence diagram tools on the market. This also means that it is possible to work with the tool offline.

The tool is developed, maintained, and used by people who create a lot of sequence diagrams in their daily work. If you have any question / comments / suggestions / bugs please contact raise a request in our Help Center or send email to info@sequencediagram.org. The more feedback we get the better we can prioritize.


Privacy and data protection information

The tool itself does not collect data, however, services it relies on, such as Content Delivery Network, hosting, and cloud storage, do. See privacy policy for details.

Are diagrams/scripts created using SequenceDiagram.org subject to any license?

No license is imposed by SequenceDiagram.org on the generated output. However, like with all images containing text, the fonts used might. The default font used in diagrams is the default sans-serif font selected by your browser. You can specify a different font using the fontfamily keyword, see help for more information.

On which platforms is SequenceDiagram.org available?

See menu "Help" -> "Platforms & API"

How do I generate a PDF of my sequence diagram?

Zoom to a chosen level in the editor and Print to PDF from your browser. The print css makes sure to only show the diagram on the page.

Are there any example sequence diagrams?

Yes, clicking the help menu and selecting "Instructions" will show examples of all possible diagram elements. A copy icon is available for copying the source text.
You can also ask ChatGPT to "Create a detailed sequence diagram for TLS 1.3 handshake using textual sequencediagram.org syntax"

Is the codebase of SequenceDiagram.org open source?

No, the codebase is currently not available under any open source license

What libraries are used by SequenceDiagram.org?

  • lz-string is used to create URLs for sharing sequence diagrams. LICENSE
  • Canvas2Svg is used to export the diagram into SVG file format. LICENSE
  • CodeMirror is used as the text editor. LICENSE
  • Font Awesome is used to provide icons for the icon participants. LICENSE
  • Material Design Icons is used to provide icons for the icon participants. Color of the icons is altered based on input. LICENSE
  • Font Awesome 5 Free is used to provide icons for the icon participants. LICENSE
  • Font Awesome 6 Free is used to provide icons for the icon participants. Color of the icons is altered based on input. LICENSE
  • RBush is used for collision detection calculations for onmousemove events. LICENSE
  • DomPurify is used as a safeguard when embedding SVG files from Font Awesome and Material Design Icons. LICENSE
  • MSAL.js from Microsoft is used for authentication towards Microsoft services.
  • OneDrive.js from Microsoft is used for file picker for OneDrive and SharePoint.
  • gsi/client and api.js from Google is used for authentication towards Google services and file picker for Google Drive and Team Drives.

SequenceDiagram.org and its services are provided by NoSpareTime AB, a private limited company.

Platforms & API

Below follow descriptions of all available platforms and APIs.


Atlassian Confluence Cloud

Intellij IDEA

  • JetBrains Marketplace link: SequenceDiagram.org Plugin
  • Enables creating, editing, and saving SequenceDiagram.org files inside Intellij.
  • Select this for an offline/desktop version.

On-Prem (Docker)

  • The SequenceDiagram.org web application for internal use within a company (may be deployed on-prem or in public cloud but access must be restricted the company only).
  • The Docker image is built using Caddy as the base image. Mount a new Caddyfile to configure HTTPS or add additional Docker layers as you see fit.
  • The cost is $900 and includes a perpetual license and one year of free updates (i.e. you can keep using the software indefinitely but the license must be renewed to request updated versions after one year has passed).
  • For any questions or to order, please create a Support request with medium priority in the Help Center or send email to info@sequencediagram.org.

JavaScript API (for Selenium and similar tooling)

  • Provides the possibility to generate diagrams from local machine or Jenkins using Python and Selenium Grid Standalone with Chrome and similar tooling
  • The API is available on SequenceDiagram.org and in On-Prem (Docker).
  • How-to-guide
    1. Run the selenium/standalone-chrome container
      docker run -d -p 4444:4444 -e SE_START_XVFB=false -e SE_NODE_MAX_SESSIONS=2 -e SE_NODE_SESSION_TIMEOUT=30 --shm-size="2g" selenium/standalone-chrome:4.19.1-20240402
    2. Install the Selenium Python package
      pip install selenium
    3. Copy the following code into a Python file named "diagramtest.py"
      from selenium import webdriver import base64 # connect to the Selenium/standalone-chrome container options = webdriver.ChromeOptions() options.add_argument("--headless=new") driver = webdriver.Remote(command_executor='http://localhost:4444', options=options) # load https://sequencediagram.org or URL of the Docker On-Prem version of SequenceDiagram.org driver.get("https://sequencediagram.org") # get diagram source text diagram_source = "title Test\nnote over A: I'm a note" # generate PNG Data URL png_data_url = driver.execute_async_script(   "const callback = arguments[arguments.length - 1];" +   "SEQ.api.generatePngDataUrl(arguments[0], callback)",   diagram_source) # write to a PNG image file png_base64_data = png_data_url.split(",")[1] png_image_data = base64.b64decode(png_base64_data) with open("result.png", "wb") as f:   f.write(png_image_data) # generate SVG Data URL svg_data_url = driver.execute_async_script(   "const callback = arguments[arguments.length - 1];" +   "SEQ.api.generateSvgDataUrl(arguments[0], callback)",   diagram_source) # write to an SVG image file svg_base64_data = svg_data_url.split(",")[1] svg_image_data = base64.b64decode(svg_base64_data) with open("result.svg", "wb") as f:   f.write(svg_image_data) print('Diagrams result.png and result.svg generated and saved to disk') driver.quit()
    4. Run the diagramtest.py script to generate diagram image files in the current folder (result.png and result.svg)
      python3 diagramtest.py
    5. Feel free to send a question if you ran into any issues (if you don't want to use Python, use any other Selenium-supported language)

Google Drive

  • Google Workspace Marketplace link: SequenceDiagramOrg App
  • Enables the direct opening of SequenceDiagram.org files from Google Drive.

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