Open-source Lucidchart alternatives

Excalidraw is a browser-based whiteboard that renders shapes, arrows and text in a deliberately hand-drawn style, which makes diagrams feel like quick sketches rather than polished slides. It is used for architecture diagrams, wireframes, brainstorming and teaching, and works on an infinite canvas with zoom and pan.

The editor offers rectangles, circles, diamonds, arrows, lines, free-draw and an eraser, along with labeled arrows that stay bound to shapes, image support, shape libraries, dark mode and undo and redo. Drawings export to PNG, SVG or the clipboard, or to an open JSON-based .excalidraw file. The hosted app adds real-time collaboration with end-to-end encryption, offline use as a progressive web app, autosave in the browser and shareable read-only links.

The editor is also published as an npm package under the MIT license, so developers can embed it in their own products and customize it. A separate paid plan, Excalidraw+, is linked from the project for people who want a hosted workspace.

Drawnix is a free, open-source whiteboard that brings mind maps, flowcharts and freehand drawing together in a single workspace. Instead of switching between separate diagramming apps, you can sketch ideas, structure them into diagrams and annotate everything on one infinite canvas that you can zoom and scroll freely.

The editor supports inserting images, undo and redo, copy and paste, light and dark themes, and a layout that adapts to mobile devices. Mermaid syntax can be converted into flowcharts and Markdown text into mind maps, while work is saved automatically in the browser and can be exported as PNG images or as .drawnix JSON files for later reuse.

Drawnix is released under the MIT licence and is built on Plait, an open-source drawing framework from the PingCode team, using a plugin architecture that can work with different UI frameworks. The hosted app at drawnix.com is a minimal version, and the repository includes Docker instructions for people who prefer to run their own copy.

draw.io is a diagramming and whiteboarding application, with many configuration options, written in JavaScript and running entirely in the browser. It is co-owned and built by draw.io Ltd (formerly JGraph) and draw.io AG, and the same code powers the production deployment at app.diagrams.net.

The repository's source code uses the Apache License 2.0, while the icon sets, stencil libraries and diagram templates come with extra terms, including a restriction on using them in Atlassian products or marketplace plugins without written permission, although diagrams you create are unaffected and the project makes no copyright claim on them. The scope is diagramming and whiteboarding, not SVG editing, and this version does not offer real-time collaborative editing.

The team does not accept pull requests; development is done entirely by the core team. Because the editor is client-side, it can be embedded or hosted on your own infrastructure, and the hosted app is free to use in a browser. It suits anyone drawing flowcharts, architecture diagrams, network maps or UML.

TheOneFile is a visual planning and replay environment that lives in a single HTML file. It lets you map anything made of nodes and connections, such as networks, smart homes, sports plays, mind maps, facilities and infrastructure, and it works offline, opens in a browser and saves changes back into itself.

The core edition offers shapes, lines and full styling, animated zones, replay video export and encryption of saved data. A Networkening edition adds live status monitoring and icon sets from selfh.st, Material Design Icons and Simple Icons while remaining a single file. TheOneFile Verse is a Docker-based wrapper that adds real-time collaboration so multiple users can create, edit and share diagrams together.

Online demos exist for corporate and homelab examples, and the repository topics point to use as air-gapped or break-glass documentation, with OIDC and SSO also mentioned. The repository metadata lists the license as Other, so check the license file for the exact terms.