Multimeter

AI-powered REST Client and API testing in VS Code. Git-native alternative to Postman. YAML .mmt files.

Demo · Website · Request Feature · VS Code · CLI · GitHub Action · Docs · llms.txt

🚀 Start with a request. Grow into a platform.

Multimeter is Git-native API testing in VS Code. Requests, tests, mocks, and docs are YAML .mmt files in your repo.

Start with a single HTTP request.

Grow into tests, suites, mocks, reports, documentation, and CI when you need them.

All in the same tool. No migration. No second product.

🎯 What you get

Simple by default

• ✅ Git-native, file-based YAML
• ✅ Lightweight — no account, no cloud lock-in
• ✅ Collaboration through pull requests, like code
• ✅ The same files locally and in CI

A full testing platform when you need it

• ✅ HTTP, WebSocket, GraphQL, and gRPC
• ✅ Multi-step flows and test suites
• ✅ Mock servers
• ✅ Generated documentation
• ✅ Reports
• ✅ CI with testlight

AI in the same files

• ✅ Generate tests from an API or a description (Cursor, Copilot, Claude via MCP)
• ✅ Judge replies — semantic similarity, or open-ended checks like how funny a response is
• ✅ Bring your own model (Ollama or cloud)

See all features →

⚡ Start simple

Multimeter is a VS Code-native extension. All you need:

• Click Install button in Multimeter VS Code Extension
• Open Get Started from the Activity bar and follow the instructions

There you run a POST request as follows:

type: api
title: Simple POST
url: https://test.mmt.dev/echo
method: post
format: json
body:
  message: hello

That's enough.

• No suites.
• No mocks.
• No workflows.
• No complexity.

🧪 Need tests?

type: test
steps:
  - http: https://test.mmt.dev/echo
    method: get
    expect:
      status: 200

• Still simple.
• Still Git-native.
• Still easy to review.

🚀 Scale without switching tools

As your project grows, Multimeter grows with it.

Add:

• Test suites
• Mock servers
• Documentation
• Workflow execution
• Structured reporting
• CI artifacts

Only when you need them.

Everything stays in the same ecosystem.

[See all examples →](./examples)

🤖 MCP, AI generation, and AI judges

Cursor, Copilot, and Claude write and run the same .mmt files you edit in VS Code. MCP (mmt-mcp) gives them scaffold_test, validate, format, and run — generate tests from an API or a description, then keep them in Git.

Judge an API answer in the same test. Compare semantic similarity to an expected reply, or check something open-ended — for example, how funny the response is. Bring your own model (Ollama or cloud). An alternative to a separate Promptfoo eval stack.

See MCP docs · Judge docs

🔁 Built for reliable CI

Multimeter validates test definitions before execution.

That means:

• ✅ Earlier feedback
• ✅ More deterministic execution
• ✅ Fewer surprises in CI
• ✅ Easier debugging
• ✅ Reproducible results

GitHub Actions:

- uses: actions/checkout@v4
- uses: mshobeyri/testlight-action@v1
  with:
    file: tests/suite.mmt
    report: junit
    report-file: results/junit.xml

Or from a terminal using the Multimeter CLI called testlight.

npm install -g mmt-testlight
testlight run tests/suite.mmt

See the GitHub Action and Testlight install.

📦 Everything stays in Git

Your code, tests, mocks, documentation, reports, and environment settings live in the same repository.

• ✅ Version controlled
• ✅ Code and tests evolve together
• ✅ Reviewable through pull requests
• ✅ Easy to move and share
• ✅ No platform lock-in
• ✅ AI can update code and tests together
• ✅ Environment variables never go missing
• ✅ Historical test results stay with the project

🧠 Philosophy

Most API tools focus on requests.

Multimeter focuses on behavior.

Instead of asking:

> "Did this request return the expected response?"

Multimeter helps you answer:

> "Does this system still behave correctly?"

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License

Multimeter is licensed under the [Apache License 2.0](LICENSE.md).

Demos · [Documentation](./docs/toc.md) · Website · GitHub

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: mshobeyri
• Source: mshobeyri/multimeter
• License: Apache-2.0
• Homepage: https://mmt.dev

Install and usage instructions live in the source repository linked above.