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GripMock

gripmock.org

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Spec score 7.7 #16 of 24 in gRPC Tools

What it is

GripMock is a mock server for gRPC services that returns responses defined in YAML or JSON without requiring a backend. It supports unary, server-streaming, client-streaming, and bidirectional calls. Stubs can match request inputs and headers using rules such as equals, contains, matches, anyOf, and glob; dynamic templates can form responses from request payloads, headers, and stream position. Stubs can also return gRPC status errors or delayed responses for timeout testing. The web dashboard lists used and unused stubs and allows them to be created, edited, or deleted while the server runs. GripMock loads .proto files or compiled .pb descriptors, including descriptors supplied to a running server, and can start from a Buf Schema Registry module reference. Deployment options include Docker, release binaries, Homebrew, shell scripts, and Go; a Go SDK embeds it in a test process. It also supports native TLS, optional mutual TLS, OTLP traces, a /metrics endpoint, and MCP endpoints for AI agents. It is free and MIT-licensed.

Spec sheet

What it does
GripMock is a mock server for gRPC services that serves responses defined in YAML or JSON without requiring a backend.Read 30 Sep 2026 · gripmock.org
Purpose
GripMock is a mock server for gRPC services that serves responses defined in YAML or JSON without a backend.Read 30 Sep 2026 · gripmock.org
Deployment
The project documents installation through Docker, release binaries, Homebrew, shell script, and Go install.Read 30 Sep 2026 · gripmock.org
Integrations
The documentation lists a Model Context Protocol API, an official GitHub Actions integration, and OpenTelemetry trace export over OTLP.Read 30 Sep 2026 · gripmock.org
Security
GripMock supports native TLS for gRPC and optional mutual TLS client-certificate authentication.Read 30 Sep 2026 · gripmock.org
Support
The documentation directs bug reports and questions to GitHub issues.Read 30 Sep 2026 · gripmock.org
License
The project is released under the MIT License.Read 30 Sep 2026 · gripmock.org
AI tooling
GripMock provides Model Context Protocol endpoints for AI agents and tool-driven automation.Read 30 Sep 2026 · gripmock.org
Descriptors
GripMock can load compiled .pb descriptors, including from a running server without restarting it.Read 30 Sep 2026 · gripmock.org
Dynamic responses
Dynamic templates can build responses from request payloads, headers, and stream position.Read 30 Sep 2026 · gripmock.org
Embedded SDK
A Go SDK runs GripMock inside the test process, without starting a container or external binary.Read 30 Sep 2026 · gripmock.org
Failure testing
Stubs can return gRPC status errors or delay responses to exercise client timeouts.Read 30 Sep 2026 · gripmock.org
Intended use
The project describes Docker use for local development, CI, and containerized test environments.Read 30 Sep 2026 · gripmock.org
Matching
Stub matching supports exact, partial, regex, glob, and header matching, with priority rules.Read 30 Sep 2026 · gripmock.org
Metrics
GripMock exposes a `/metrics` endpoint for Prometheus scraping.Read 30 Sep 2026 · gripmock.org
Observability
It can export traces over OTLP and exposes a /metrics endpoint for scraping.Read 30 Sep 2026 · gripmock.org
Protocol files
It can load `.proto` files or compiled `.pb` descriptors, including descriptors pushed to a running server without restarting it.Read 30 Sep 2026 · gripmock.org
Runtime dashboard
The dashboard at `http://localhost:4771/` lists loaded and matched stubs and allows editing without restarting the server.Read 30 Sep 2026 · gripmock.org
Runtime editing
The web dashboard can create, edit, and delete stubs, and show used and unused stubs.Read 30 Sep 2026 · gripmock.org
Schema registry
GripMock can start from a Buf Schema Registry module reference.Read 30 Sep 2026 · gripmock.org
Streaming
It supports unary, server-streaming, client-streaming, and bidirectional gRPC calls.Read 30 Sep 2026 · gripmock.org
Stub matching
Stubs can match requests by input and headers using equals, contains, matches, anyOf, and glob rules.Read 30 Sep 2026 · gripmock.org

Strong points and limits

Strong points

  • Supports four gRPC call patterns
  • Matches requests by inputs and headers
  • Runtime stub editing in a web dashboard
  • Loads .proto files and compiled descriptors
  • Free and MIT-licensed

Limits

  • Designed for gRPC services
  • Bug reports and questions go through GitHub issues

Who it suits

GripMock suits developers building or testing gRPC clients without a backend, including local development, CI, and containerized test environments. Its dashboard and embedded Go SDK may suit teams that want to manage stubs during testing or run the mock server inside a test process.

Verdict

GripMock covers request matching, streaming, and runtime stub editing for gRPC mock-server work. Its open-source, self-hosted approach is worth considering if those capabilities fit your test setup.

Where Specifiction places it

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