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Testing48k · #2168

api-testing-observability-api-mock

Lets your agent create realistic API simulations. This is useful for testing systems without relying on the real API.

What it does

This tool helps create 'fake versions' of APIs (internet services) so developers can test their programs without needing to use the real services. It simulates how the actual API would behave.

When to use it

  • ✓To test how an application behaves with an API.
  • ✓To simulate a service that doesn't exist yet.
  • ✓To create demonstrations of how a system works.

Example of what to ask your AI

“Create a mock for a login API that returns a success token or an error message.”

Want more? Open the sections below.

How to use

The easiest way: copy the message below and paste it into Claude, ChatGPT, Cursor or any AI. It reads the skill and follows the instructions.

Skill link

https://github.com/sickn33/agentic-awesome-skills/blob/main/plugins/agentic-awesome-skills-claude/skills/api-testing-observability-api-mock/SKILL.md

Ready-to-paste message

Use this skill to help me: https://github.com/sickn33/agentic-awesome-skills/blob/main/plugins/agentic-awesome-skills-claude/skills/api-testing-observability-api-mock/SKILL.md Read the SKILL.md file at that link and follow its instructions for my task.
How it works

You describe how the real API works (the contract), and the tool creates a fake service that mimics these responses. This allows other parts of the system to be developed and tested independently.

Installation

Easiest way: copy the skill link and paste it into Claude, ChatGPT or Cursor asking it to follow the instructions.

In the terminal (Claude Code, Codex, Cursor), in your project folder:

npx skills add sickn33/agentic-awesome-skills --skill api-testing-observability-api-mock

Or download just the file:

curl -L https://raw.githubusercontent.com/sickn33/agentic-awesome-skills/main/plugins/agentic-awesome-skills-claude/skills/api-testing-observability-api-mock/SKILL.md -o SKILL.md
Technical content (original SKILL.md)

Original text by the author, straight from GitHub.

API Mocking Framework

You are an API mocking expert specializing in creating realistic mock services for development, testing, and demonstration purposes. Design comprehensive mocking solutions that simulate real API behavior, enable parallel development, and facilitate thorough testing.

Use this skill when

  • Building mock APIs for frontend or integration testing
  • Simulating partner or third-party APIs during development
  • Creating demo environments with realistic responses
  • Validating API contracts before backend completion

Do not use this skill when

  • You need to test production systems or live integrations
  • The task is security testing or penetration testing
  • There is no API contract or expected behavior to mock

Safety

  • Avoid reusing production secrets or real customer data in mocks.
  • Make mock endpoints clearly labeled to prevent accidental use.

Context

The user needs to create mock APIs for development, testing, or demonstration purposes. Focus on creating flexible, realistic mocks that accurately simulate production API behavior while enabling efficient development workflows.

Requirements

$ARGUMENTS

Instructions

  • Clarify the API contract, auth flows, error shapes, and latency expectations.
  • Define mock routes, scenarios, and state transitions before generating responses.
  • Provide deterministic fixtures with optional randomness toggles.
  • Document how to run the mock server and how to switch scenarios.
  • If detailed implementation is requested, open resources/implementation-playbook.md.

Resources

  • resources/implementation-playbook.md for code samples, checklists, and templates.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
FAQ

What is an API?

An API is like a menu that one program uses to request information or actions from another program.

What is a 'mock'?

A 'mock' is a fake or simulated version of something, used for testing or development.

Can I use this to test a website's security?

No, this tool is for simulating normal API behavior, not for testing security vulnerabilities.

Details

Original description by the author

You are an API mocking expert specializing in realistic mock services for development, testing, and demos. Design mocks that simulate real API behavior and enable parallel development.

repo: sickn33/agentic-awesome-skills

Popularity

GitHub stars
48k
Ranking position
#2168
License
MIT
Updated
10/15/2026

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