Kroki
Kroki provides one API for generating diagrams from textual descriptions using libraries such as Mermaid, PlantUML, Graphviz, and D2.
About Kroki
Kroki is a web-based HTTP API that generates diagrams from text descriptions. A single API accepts input for many diagram libraries, including Mermaid, PlantUML, Graphviz, D2, Vega-Lite, and WaveDrom. Requests can be sent as GET or POST, and output formats depend on the diagram type, with SVG, PNG, and PDF among the options.
Kroki is available as a free hosted service and as a self-managed installation on your own infrastructure or in a cloud environment. The free service is run on servers offered by Exoscale, but some parts of the infrastructure are hosted with other providers, and the operators say they are still seeking sponsors to cover expenses. The self-managed option requires Linux experience to install.
Key features
- Unified API for many diagram libraries, including Mermaid, PlantUML, and Graphviz
- HTTP GET and POST requests for generating diagrams
- POST option that accepts diagram source as plain text
- Output formats vary by diagram type, such as SVG, PNG, or PDF
- Cheat sheet listing each diagram type, its output formats, and URL slug
- Self-managed installation on your own infrastructure or cloud environment
Best for: Developers and technical writers who want to generate diagrams from text through an HTTP API without installing each diagram library.
Good for
- Hosted free service means users do not need to install diagram libraries
- One API covers multiple diagram syntaxes, so users learn one interface
- Plain text POST requests avoid the need for deflate and base64 encoding
Watch out for
- Self-managed installation requires Linux experience
- The free service depends on sponsorship to cover some expenses
- Supported output formats differ by diagram type, so not every format is available for each library
Kroki at a glance
- Website
- kroki.io
- Category
- Design & Creative › Charts & Data Visualization
- Type
- Online tool
- Pricing
- Not confirmed. Check the site
- Platforms
- Web
- Open source
- Not stated
- Language
- English
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
Guides for Charts & Data Visualization
Kroki alternatives
Tools and sites you could use instead, ranked by how closely they match.
PlantText provides an online editor for PlantUML code and generates class, sequence, activity, and state diagrams.
Kroki CLI converts diagram files through the Kroki service, inferring diagram type from the file extension by default.
Open source
24 alternativesSankeyMATIC builds flow diagrams for comparing quantities across stages, with examples covering budgets, results, and processes.
UMLet provides free, open source UML drawing with a simple interface for making diagrams, including sequence and activity diagrams.
text2diagram creates diagrams and charts from text descriptions, with real-time collaboration and document permissions listed on its page.
PlantUML generates UML and other diagrams from textual descriptions and exports results in formats including PNG, SVG, and PDF.
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Kroki FAQ
How do I send a diagram to Kroki?
You can send the diagram as plain text using a POST request. You can also use a GET request, where the diagram is encoded in the URL using deflate and base64. The documentation includes examples in Node.js, JavaScript, Java, Python, and Go.
Can I run Kroki on my own servers?
Yes. Kroki can be downloaded and installed on your own infrastructure or in a cloud environment. The site notes that the self-managed version requires Linux experience to install, and it refers to the documentation for installation steps.
What if my diagram tool is not listed?
The site asks users to contact the team by email if a favorite diagram tool is missing from the list.
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