Kroki

API

Diagram rendering API for PlantUML, Mermaid, Graphviz, D2 and more

Price: Free, open source
Access: None

Docs
Repo

About

Open-source HTTP API that turns text diagram sources such as PlantUML, Mermaid, Graphviz, D2 and BPMN into SVG, PNG or PDF. A free public instance runs at kroki.io, and you can self-host it with Docker. MIT licensed.

What you can do with it

Render Mermaid, PlantUML or Graphviz text into SVG or PNG images
Embed diagrams in docs with a GET URL that encodes the diagram source
Self-host a diagram server with Docker for private documentation

Get started

POST the diagram source to https://kroki.io; no key is needed
Or run the yuzutech/kroki Docker image yourself

Example

curl -X POST https://kroki.io/ \
  -H "Content-Type: application/json" \
  -d '{"diagram_source": "digraph G {Hello->World}", "diagram_type": "graphviz", "output_format": "svg"}' \
  -o diagram.svg

Details

Hosting: Hosted service, Self-hosted
Available in: Worldwide
MCP server: None