Overview

Like an API client focused on gRPC rather than REST, grpcui helps developers explore services and make calls through a web UI. It can find schemas through server reflection, .proto files, or compiled protoset files, so it works with several common ways of supplying service definitions.

The project is MIT-licensed, permitting users to use, modify, and contribute to it freely. Its focus is narrow: it does not support GraphQL or WebSocket, and it does not provide automated test runs or API documentation. Choose it for interactive gRPC work, not as an all-purpose API platform.

Key features

Schema-aware request editing

Dynamic HTML forms build protobuf messages, including well-known types, oneofs, and maps. This gives developers a structured way to compose calls, while a dedicated text form accepts a complete JSON request body for those who prefer to work directly with payloads.

Call inspection and transport options

After an RPC, grpcui shows headers, response messages or errors, and trailers, with human-readable HTML tables. It supports plaintext and TLS connections, including mutual TLS with client certificates—useful when a service requires client authentication as well as encryption.

Streaming trade-off

All RPC method types are supported, including streaming, but streaming requests must be constructed all at once. Bidirectional streams cannot be interacted with like they can in grpcurl. That makes grpcui a less suitable choice when a developer needs to send and respond to messages incrementally during a live bidirectional call.

Embedding and installation

Go packages let developers embed either a gRPC web form or a complete standalone web UI in a Go HTTP server. Installation is documented through Homebrew on macOS or Linux and through Go's install command; a container image is also provided as ghcr.io/fullstorydev/grpcui:v1.5.4.

Pricing

Open-source grpcui: 0.00 USD per free. The MIT license allows use, modification, and contribution without a paid tier. This is a straightforward fit for individual developers and teams comfortable using open-source software; there are no plan tiers to trade features or seats against cost.

Platforms

grpcui is listed for Linux, macOS, Windows, self-hosted use, and the web. Its command-line installation routes and browser interface make it a tool for developers working across supported operating systems, while its Go packages also support embedding in a Go HTTP server.

Who it's for

grpcui is best for developers who need to discover gRPC services, shape requests, and examine responses in a browser-based workflow. It is a particularly sensible choice when server reflection or local schema files are available and plaintext, TLS, or mutual TLS connections are needed. Developers who must actively exchange messages within bidirectional streams should look elsewhere.

Pros and cons

Pros: Multiple schema sources—reflection, .proto, and protoset—make it adaptable to different service setups.
Pros: Structured protobuf forms and full JSON-body entry accommodate both guided request building and direct payload editing.
Pros: Response headers, messages or errors, and trailers are shown together, and mutual TLS is supported.
Pros: MIT licensing and Go embedding packages make it usable and adaptable in Go-based environments.
Cons: Streaming requests must be prepared all at once, limiting control over bidirectional exchanges.
Cons: It does not cover GraphQL, WebSocket, automated test runs, or API documentation, so it cannot replace a broader API suite for those jobs.

Alternatives

Kreya is worth considering for developers who prefer a freemium client with a free plan and trial across Linux, macOS, and Windows; its free plan limits request history to the latest request, and it is not open source.

Bandura may suit users seeking a free client for personal and commercial use without an account, paid seats, or feature tiers; a commercial licence is also offered for 59.00 USD per once.

Evans is another free, open-source gRPC client for Linux, macOS, and Windows.

FintX offers a free/open-source plan with unlimited gRPC clients, saved requests, import/export, method tabs, a JSON editor, and projects for developers wanting those workflow features.

grpcmd provides a free CLI for sending requests, starting a server, reflection, and listing or describing methods; its JavaScript scripting is also relevant to developers who want scripting in their client.

ghz is a free option for gRPC load testing, with a complementary web application in beta.

GripMock is another free gRPC tool to consider.

BloomRPC Extended is another free option for Linux, macOS, and Windows.

Explore more in gRPC Tools or API clients.

Verdict

Choose grpcui if you want a free, MIT-licensed way to build and inspect gRPC calls through a browser, with flexible schema discovery and support for mutual TLS. Look elsewhere if interactive bidirectional streaming is central to your work, or if you need GraphQL, WebSocket, automated testing, or API documentation.

	grpcui	WhoisJSON API
Free plan	Yes	Yes
Free trial	No	No
Paid from	Free	$10/mo
Open source	No	No
Platforms	Linux, macOS, self-hosted, Web, Windows	—
Free plan	Yes	Yes
GraphQL support	No	—
gRPC support	Yes	—
WebSocket support	No	—
Automated test runs	No	—
API documentation	No	Yes
Team workspaces	No	—
Available platforms	web_and_desktop	—

grpcui vs WhoisJSON API

grpcui

WhoisJSON API