grpcui

grpcui is a command-line utility that opens a browser-based interface for calling gRPC services. It suits developers exploring service behavior or shaping requests without leaving a CLI-driven workflow. Its schema-aware forms and broad RPC coverage are useful, though bidirectional streaming is less interactive than in grpcurl.

Overview

grpcui brings a Postman-like approach to gRPC rather than REST: it discovers service definitions through server reflection, .proto files, or compiled protoset files, then lets developers build calls in a browser. That makes it a focused option for inspecting a service when its schema can be supplied or discovered.

It is MIT-licensed open source, so users can use, modify, and contribute to the project freely. It is not a broad API suite: GraphQL, WebSocket, automated test runs, and API documentation are outside its scope.

Key features

Schema-aware request building

Dynamic HTML forms cover protobuf messages, including well-known types, oneofs, and maps. Developers who would rather work directly with payloads can enter or paste a full JSON request body. The combination is useful for both guided exploration and precise request editing.

RPC coverage and its streaming caveat

grpcui supports all RPC method types, including streaming, but streaming requests have to be assembled all at once. Bidirectional calls cannot be steered interactively like they can in grpcurl, which makes grpcui a weaker fit for debugging exchanges that depend on sending and receiving messages incrementally.

Responses, security, and embedding

After a call, the interface shows response headers, messages or errors, and trailers, with human-readable HTML tables. Plaintext and TLS connections are supported, including mutual TLS with client certificates. Go packages also let developers embed either a gRPC form or a complete standalone gRPC web UI in a Go HTTP server.

Pricing

grpcui is free: its open-source plan costs nothing under the MIT license, with permission to use, modify, and contribute. There is no paid tier or trial to weigh against a feature-limited free edition; the trade-off is that the tool remains focused on interactive gRPC calls rather than testing or broader API workflows.

Platforms

The interface runs in a web browser, while the tool is installed through the command line. Installation is documented through Homebrew on macOS or Linux and through Go install; a container image is also published as ghcr.io/fullstorydev/grpcui:v1.5.4. The project supports Linux, macOS, Windows, and self-hosted use.

Who it's for

grpcui is a good match for developers who need to discover gRPC methods, construct protobuf requests, and inspect responses during service development or troubleshooting. Go teams that want to embed a gRPC form in an HTTP server have an additional use for its packages. Teams seeking automated test runs, API documentation, or GraphQL and WebSocket support should choose a broader tool.

Pros and cons

• Flexible schema discovery: Reflection, source .proto files, and compiled protosets provide several ways to load service definitions.
• Useful request controls: Dynamic protobuf forms and a full JSON body editor accommodate different working styles.
• Strong connection coverage: Plaintext, TLS, and mutual TLS with client certificates support a range of server setups.
• Streaming interaction is limited: Calls can use streaming methods, but requests must be constructed all at once and bidirectional exchanges are not interactive like grpcurl.
• Narrow API scope: It does not cover GraphQL, WebSocket, automated test runs, or API documentation.

Alternatives

Kreya is worth considering for users who want a freemium client with a free trial and Linux, macOS, and Windows support; its free plan is for individuals and retains only the latest request in history.

Bandura is another free option for Linux, macOS, Windows, and self-hosted use, with personal and commercial use, no account, no paid seats, and no feature tiers on its free plan. FintX has a free/open-source plan with unlimited gRPC clients, autosaved requests, import and export, tabs per method, a JSON editor, and projects; it supports Linux, macOS, and Windows.

grpcmd offers a free yearly plan for sending requests, starting a server, reflection, method inspection, and JavaScript scripting on Linux, macOS, and Windows. Evans is an open-source gRPC client for Linux, macOS, and Windows. For load testing, ghz is an open-source gRPC CLI and Go package, with a complementary web application in beta. GripMock and BloomRPC Extended are also free alternatives.

Browse more options in gRPC Tools or API clients.

Verdict

Choose grpcui if you want a free, open-source browser interface for constructing schema-aware gRPC requests and examining responses, especially when you value reflection, TLS support, or Go embedding. Look elsewhere when interactive bidirectional streaming or a wider API workflow is central to the job.