GitHub - CopilotKit/aimock: Mock everything your AI app talks to — LLM APIs, MCP, A2A, vector DBs, search. One package, one port, zero dependencies.

Mock infrastructure for AI application testing — LLM APIs, MCP tools, A2A agents, vector databases, search, rerank, and moderation. One package, one port, zero dependencies.

Quick Start

npm install @copilotkit/aimock

import { LLMock } from "@copilotkit/aimock";

const mock = new LLMock({ port: 0 });
mock.onMessage("hello", { content: "Hi there!" });
await mock.start();

process.env.OPENAI_BASE_URL = `${mock.url}/v1`;

// ... run your tests ...

await mock.stop();

The aimock Suite

aimock mocks everything your AI app talks to:

Tool	What it mocks	Docs
LLMock	OpenAI, Claude, Gemini, Bedrock, Azure, Vertex AI, Ollama, Cohere	Providers
MCPMock	MCP tools, resources, prompts with session management	MCP
A2AMock	Agent-to-agent protocol with SSE streaming	A2A
VectorMock	Pinecone, Qdrant, ChromaDB compatible endpoints	Vector
Services	Tavily search, Cohere rerank, OpenAI moderation	Services

Run them all on one port with npx aimock --config aimock.json, or use the programmatic API to compose exactly what you need.

Features

Record & Replay — Proxy real APIs, save as fixtures, replay deterministically forever
11 LLM Providers — OpenAI, Claude, Gemini, Bedrock, Azure, Vertex AI, Ollama, Cohere — full streaming support
MCP / A2A / Vector — Mock every protocol your AI agents use
Chaos Testing — 500 errors, malformed JSON, mid-stream disconnects at any probability
Drift Detection — Daily CI validation against real APIs
Streaming Physics — Configurable ttft, tps, and jitter
WebSocket APIs — OpenAI Realtime, Responses WS, Gemini Live
Prometheus Metrics — Request counts, latencies, fixture match rates
Docker + Helm — Container image and Helm chart for CI/CD
Zero dependencies — Everything from Node.js builtins

CLI

# LLM mocking only
npx aimock -p 4010 -f ./fixtures

# Full suite from config
npx aimock --config aimock.json

# Record mode: proxy to real APIs, save fixtures
npx aimock --record --provider-openai https://api.openai.com

# Docker
docker run -d -p 4010:4010 -v ./fixtures:/fixtures ghcr.io/copilotkit/aimock -f /fixtures

Switching from other tools?

Step-by-step migration guides: MSW · VidaiMock · mock-llm · Python mocks · Mokksy

Documentation

https://aimock.copilotkit.dev

Real-World Usage

AG-UI uses aimock for its end-to-end test suite, verifying AI agent behavior across LLM providers with fixture-driven responses.

License

MIT