Kroki provides a unified API with support for BlockDiag (BlockDiag, SeqDiag, ActDiag, NwDiag, PacketDiag, RackDiag), BPMN, Bytefield, C4 (with PlantUML), D2, DBML, Diagrams.net (experimental), Ditaa, Erd, Excalidraw, GraphViz, Mermaid, Nomnoml, Pikchr, PlantUML, SvgBob, Symbolator, UMLet, Vega, Vega-Lite, WaveDrom and WireViz… and more to come!
This section offers a basic tutorial for evaluating Kroki. More comprehensive installation instructions are in the Kroki documentation.
Kroki uses a simple algorithm (deflate + base64) to encode your diagram in the URL:
GET /plantuml/svg/SyfFKj2rKt3CoKnELR1Io4ZDoSa70000
You can also call Kroki with POST:
POST /
{
"diagram_source": "Bob -> Alice : hello",
"diagram_type": "plantuml",
"output_format": "svg"
}In this case, you don’t need to encode your diagram.
It’s also possible to send your diagram as plain text using the Content-Type header.
The output format will be specified using the Accept header and the diagram source will be sent as the request body:
POST /plantuml
Accept: image/svg+xml
Content-Type: text/plain
Bob -> Alice : helloYou can also define the output format in the URL if you don’t want to add an Accept header:
POST /plantuml/svg
Content-Type: text/plain
Bob -> Alice : helloThe same concept applies when sending the diagram as JSON:
POST /plantuml/svg
{
"diagram_source": "Bob -> Alice : hello"
}Kroki has a modular architecture:
- server
-
A Java web server (powered by Vert.x) that acts as a gateway. Kroki server is built using Maven.
- umlet
-
A tiny Java API on top of UMlet (mini) to generate diagrams.
- nomnoml
-
A Node.js CLI on top of the Nomnoml diagram library.
- vega
-
A Node.js CLI on top of the vega diagram library. Also supports Vega-Lite concise grammar.
- mermaid
-
A companion web server written in JavaScript (powered by micro) that provides Mermaid diagram library.
- bpmn
-
A companion web server written in JavaScript (powered by micro) that provides bpmn-js diagram library.
- bytefield
-
A Node.js CLI on top of the bytefield-svg diagram library.
- wavedrom
-
A Node.js CLI on top of the wavedrom diagram library.
- excalidraw
-
A companion web server written in JavaScript (powered by micro) that provides Excalidraw.
- diagrams.net
-
A companion web server written in JavaScript (powered by micro) that provides diagrams.net.
Once the Docker images are built, you can run Kroki using docker:
$ docker run -d -p 8000:8000 yuzutech/kroki
If you want to use one of the following diagram libraries then you will also need to start the corresponding companion container:
- yuzutech/kroki-mermaid
-
Mermaid
- yuzutech/kroki-bpmn
-
BPMN
- yuzutech/kroki-excalidraw
-
Excalidraw
- yuzutech/kroki-diagramsnet (experimental)
-
diagrams.net
You can use docker-compose to run multiple containers:
version: "3"
services:
core:
image: yuzutech/kroki
environment:
- KROKI_MERMAID_HOST=mermaid
- KROKI_BPMN_HOST=bpmn
- KROKI_EXCALIDRAW_HOST=excalidraw
ports:
- "8000:8000"
mermaid:
image: yuzutech/kroki-mermaid
expose:
- "8002"
bpmn:
image: yuzutech/kroki-bpmn
expose:
- "8003"
excalidraw:
image: yuzutech/kroki-excalidraw
expose:
- "8004"
# experimental!
diagramsnet:
image: yuzutech/kroki-diagramsnet
expose:
- "8005"$ docker-compose up -d
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