Open Source JavaScript Flowchart Software

Mermaid is a JavaScript-based diagram and flowchart generating tool that uses markdown-inspired text for fast and easy generation of diagrams and charts. Forget about using heavy tools to explain your code. Mermaid greatly simplifies documentation with its simple markdown-like script language, and offers a great range of diagram and chart options. The latest version of Mermaid comes with a number of bug fixes and enhancements, as well as a new diagram type, entity relationship diagrams. Its range of available diagrams include flowcharts, sequence diagrams, gantt diagrams and more, with new ones continuously being developed.

Pencil is built for the purpose of providing a free and open-source GUI prototyping tool that people can easily install and use to create mockups in popular desktop platforms. The latest stable version of Pencil is 3.1.0 which contains stability fixes and many new features. More details can befound in the releaste notes. Pencil provides various built-in shapes collection for drawing different types of user interface ranging from desktop to mobile platforms. Starting from 2.0.2, Pencil is shipped with Android and iOS UI stencils pre-installed. This makes it even easier to start protyping apps with a simple installation. Starting from 2.0.2 Pencil has even more shape collections included by default. The list of built-in collections now includes general-purpose shapes, flowchart elements, desktop/web UI shapes, Android and iOS GUI shapes.

ioDraw is a free online drawing software, which is used to make flow chart, mind map, Gantt chart, whiteboard, mermaid, poster, and more—no registration required. It also features AI-generated charts.

Free Java Flowchart simulator / interpreter

Dgrm.net is a lightweight JavaScript library designed for creating interactive diagrams and visual representations directly within web applications. It provides developers with tools to build flowcharts, graphs, and structured visual layouts using a flexible and extensible API. The library focuses on simplicity, allowing users to define nodes, edges, and relationships without requiring complex setup or dependencies. It supports dynamic updates, enabling diagrams to respond to user interactions or data changes in real time. The system is particularly useful for applications that require visual modeling, such as workflow editors, architecture diagrams, or educational tools. Its modular design allows customization of rendering and behavior, making it adaptable to various use cases. Overall, DgrmJS offers a practical solution for embedding diagramming capabilities into modern web interfaces.

The open source embeddable online markdown editor (component), based on CodeMirror & jQuery & Marked. The available dependents are CodeMirror, marked, jQuery, FontAwesome, github-markdown.css, KaTeX, prettify.js, Rephael.js, flowchart.js, sequence-diagram.js, and Prefixes.scss. You can enable HTML tags decode, TeX, Flowchart, sequence diagram, Emoji, FontAwesome, task lists. You can also enable image upload, [TOCM], search replace features, code fold, etc. Combine multiple JS module files used by CodeMirror to greatly reduce HTTP requests and speed up downloading. In addition, when using Require.js, because of CodeMirror's strict module dependency restrictions, the merged module files cannot be used, and multiple module files are still dynamically loaded. Newly added images, links, anchor links, code blocks, pre-formatted text and other operations pop-up dialog layers and examples.

JLink lets users author flow charts based on ISO 5807 and IBM standards. Developers can use JLink to add flowcharts to applications, serve a flow chart over the web in PDF or PNG, or dynamically create a flowchart with Javascript, Python or Ruby scripts

Create flowchart using only HTML GUI. Functions are written in JavaScript with the help of JQuery. Drawing source is in HTML and visible. Program can be used locally if open the index.htm in browser.

Wireflow is an open-source collaborative tool for designing and visualizing user experience flows and wireframes directly in the browser, aimed at UX designers, product managers, and developers who need to map out interactive user journeys without heavy graphic design tools. Unlike static flowchart apps, Wireflow’s interface focuses on quick and intuitive creation of flow diagrams that represent screens and transitions, helping teams prototype and iterate on navigation logic and interaction sequences. It supports real-time collaboration, meaning multiple people can work on the same flow simultaneously, making it useful for distributed teams and remote workshops. Users can drag and drop nodes, connect steps with directed lines, and annotate interactions, producing a visual blueprint for app behavior, website navigation, or feature flows.

This application walks you through deciding what to call a Sailboat, or an item on a Sailboat, based on your answers to a series of questions.