Mermaid

Mermaid is a JavaScript-based diagramming and charting tool that uses a Markdown-inspired text syntax to simplify the creation of complex visualizations. By treating diagrams as code (DaC), Mermaid allows developers and technical writers to integrate visual documentation directly into version-controlled repositories, ensuring that architectural diagrams evolve alongside the codebase. In the 2026 landscape, Mermaid has become the industry standard for LLM-generated visualizations; nearly every major AI model (GPT-5, Claude 4, etc.) natively outputs Mermaid syntax for technical explanations. The core library is open-source under the MIT license, while the 'Mermaid Chart' commercial entity provides enterprise-grade collaboration features. Its technical architecture leverages d3 and dagre-d3 for rendering, supporting a wide array of diagram types including flowcharts, sequence diagrams, Gantt charts, class diagrams, and Git graphs. As documentation shifts toward automation, Mermaid's ability to be rendered on-the-fly via CLI, CI/CD pipelines, or browser-side scripts makes it indispensable for modern DevOps and software engineering workflows.