Diagramming & Whiteboards

D2 is a concise scripting language that lets you generate diagrams directly from plain text. It focuses on simplicity and readability, making it easy to embed visualizations in documentation and codebases. Designed for self‑hosted environments, D2 runs in the browser and can be integrated into CI pipelines, providing free, on‑premise diagram generation without vendor lock‑in.

✦ Best for developers needing simple diagrams

Excalidraw is a free, open-source collaborative whiteboard tool that allows users to create and share diagrams, flowcharts, and other visual content in real-time. It is designed to be simple, intuitive, and highly customizable, making it a popular choice for teams and individuals looking for a flexible and collaborative drawing tool.

✦ Best for small teams and solo projects

Drawnix is an open-source whiteboard tool that integrates various features such as mind maps, flowcharts, and freehand drawing. It is designed to provide a comprehensive and collaborative platform for users to brainstorm, plan, and visualize their ideas. With its intuitive interface and robust features, Drawnix aims to enhance productivity and creativity in various settings.

✦ Best for freelancers and small teams seeking customization.

Mermaid is a simple markdown-like script language for generating diagrams and flowcharts from text. It can be used to create a variety of diagrams, including flowcharts, sequence diagrams, and Gantt charts. Mermaid is often used in documentation and can be integrated into various tools and platforms.

✦ Best for solo developers and writers

PlantUML is a tool that allows users to generate diagrams from textual descriptions. It supports a wide range of diagram types, including sequence diagrams, class diagrams, and state diagrams. Users can write their diagram descriptions in a simple, human-readable syntax, and PlantUML will generate the corresponding diagram.

✦ Best for technical writers and developers needing simple diagrams