GripMock vs grpcui

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.

grpcui is a free, open-source command-line tool for interacting with gRPC servers through a browser-based interface. It is aimed at gRPC APIs rather than REST APIs and can discover service schemas through server reflection, .proto source files, or compiled protoset files. Its interface builds dynamic forms for protobuf messages, including well-known types, oneofs, and maps, and also accepts a complete JSON request body. grpcui supports RPC methods including streaming, then displays response headers, messages or errors, trailers, and readable HTML tables. It connects to plaintext and TLS servers, including mutual TLS with client certificates. Streaming requests have a constraint: they must be constructed all at once, so bidirectional streams cannot be handled interactively like they can with grpcurl. The project also provides Go packages for embedding a form or complete web UI in a Go HTTP server. Installation is documented through Homebrew on macOS or Linux, and through the Go install command. It is released under the MIT license.