workflowstacks
devtools

CATS: Automated API Testing

Get robust API testing with CATS, a tool for startup founders and developers.
1,362 stars90 forksJavaGuide quality 8/10Updated 7/24/2026100% free · open source
What it does

CATS automatically generates, runs, and reports tests for OpenAPI endpoints with minimal configuration and no coding effort, providing robust API testing and negative testing capabilities.

When to use it
  • •When you need to test OpenAPI endpoints without manually writing test cases
  • •When you want to ensure your API is resilient to unexpected input or edge cases
  • •When you need to reduce manual testing effort and maintenance for your API
Ready-to-paste prompt
java -jar target/cats-1.0.0.jar -c config.yml -e https://your-api-endpoint.com/openapi.json
Heads up: Ensure you have Java 11 or later installed on your system, as CATS requires this version to run
Saves to your device
Use with Claude
New

Skip the builder — one click puts this in Claude, Cursor, Antigravity and more.

🛠️ Technical setup

Expect 20–40 minutes in a terminal — or let your AI agent drive it.

Try it instantly — no install
Claude Code
mkdir -p ~/.claude/skills/cats && curl -fsSL https://workflowstacks.com/api/skills/cats/claude-skill -o ~/.claude/skills/cats/SKILL.md
Open in another AI app

Opens the app with this repo with the prompt ready to go — no copy-paste needed.

Connect the whole catalog (MCP)
claude mcp add --transport http workflowstacks https://workflowstacks.com/api/mcp

Adds a WorkflowStacks connector to Claude Code: search and load any skill here by chatting.

How CATS: Automated API Testing works
Codeflow
Free to inspect

CATS: Automated API Testing is a very large Java project (~64k lines across 564 code files, plus 416 test files). It is a full software project: use it through its install path rather than reading it end to end. Last commit this month, Apache-2.0 license, has a test suite.

Size
Very large codebase
~64k lines · 564 code files · days to read — use, don't read
Setup
Developer setup
A real software project. Use it via its install path; don't expect to read it all.
Runs on
Java/JVM
No API keys detected
Java 97%Shell 1%Mustache 1%CSS 1%
Where to start reading
  1. 1
    README.md
    Start here — what it does and how to install it
  2. 2
    src/main/resources/chart.js
    Inside src/ — the main logic begins here
What's in each folder
src/Core code — the actual logic1112 files
lib/Core code — the actual logic7 files
files/Folder18 files
.github/CI / automation (GitHub Actions)7 files
images/Images & static assets7 files
.mvn/Tool / agent settings2 files
READMEHas testsDocumentedCI checksApache-2.0 licenseUpdated this month
Quick Actions
Details
Creator
Endava
Language
Java
Category
devtools
Published
4/2/2020

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