Insomnium
What Insomnium is
Insomnium is a local desktop API client for testing REST, GraphQL, WebSockets, server-sent events, and gRPC. The project says it works fully offline, without cloud services, tracking, analytics, or background communication to external servers. It is free and open source under the MIT license, with Linux, macOS, and Windows platform support.
Its gRPC client handles unary calls and server-streaming, client-streaming, and bidirectional-streaming, with .proto imports and server reflection. Requests can use metadata and chained authentication strategies such as Bearer, Basic, and GCP ID Token. An optional MCP server allows MCP-aware tools to list, inspect, create, update, delete, and run saved requests programmatically. The server is disabled by default, binds to loopback, requires a Bearer token, and uses SSE over HTTP.
Desktop downloads are offered for macOS, Windows, Ubuntu, Debian, CentOS, and Fedora. The README points Arch users to AppImage or tar.gz releases, and documents macOS installation through Homebrew and Debian or Ubuntu installation through an APT repository. Users can also build it locally with npm run app-package. The project describes Insomnium as a tool for API testing in development and production.
Who it suits
Insomnium suits developers who need a local client for testing REST, GraphQL, WebSocket, server-sent event, or gRPC APIs. Its offline operation, authentication options, and optional MCP server also suit teams that want to work with saved requests programmatically.
What it does well
- Tests REST, GraphQL, WebSockets, server-sent events, and gRPC.
- Works offline without cloud services or tracking.
- Open source under the MIT license.
- gRPC support includes streaming, .proto imports, and server reflection.
- Optional MCP server can manage saved requests programmatically.
What to know first
- It is a desktop application rather than a web client.
- The MCP server is disabled by default and requires a Bearer token.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Insomnium | Open-source API client · 100% local | Free |
As github.com lists them, read 9 Oct 2026. The maker's own page has the final word.
Getting started
- Visit https://github.com/yokomohoyo/insomnium.
- Download a desktop release for macOS, Windows, Ubuntu, Debian, CentOS, or Fedora.
- For macOS, use the documented Homebrew installation route.
- For Debian or Ubuntu, use the documented APT repository.
- Build locally with npm run app-package if you prefer the source-build route.
Verdict
Choose Insomnium if you want a free, local API client with broad protocol coverage and offline operation. Look elsewhere if you need a web-based client; Insomnium is described as a desktop application.
Questions
Is Insomnium free?
Yes. The Insomnium plan is free, and the project is open source under the MIT license.
Which API protocols does it test?
It tests GraphQL, REST, WebSockets, server-sent events, and gRPC.
Which platforms are supported?
Insomnium supports Linux, macOS, and Windows as a desktop application. Downloads are offered for macOS, Windows, Ubuntu, Debian, CentOS, and Fedora.
Does Insomnium work offline?
The project says it works fully offline and has no cloud services, tracking, analytics, or background communication to external servers.
What authentication options are available?
Requests can use metadata and chained authentication strategies, including Bearer, Basic, and GCP ID Token.
Does Insomnium have an MCP integration?
An optional MCP server lets MCP-aware tools manage saved requests programmatically. It is disabled by default, binds to loopback, requires a Bearer token, and uses SSE over HTTP.
Facts from Insomnium's own pages
- Authentication
- Requests can use metadata and chained authentication strategies, including Bearer, Basic, and GCP ID Token. · github.com, 9 Oct 2026
- Automation integration
- An optional MCP server lets MCP-aware tools list, inspect, create, update, delete, and run saved requests programmatically. · github.com, 9 Oct 2026
- Desktop downloads
- Downloads are offered for macOS, Windows, Ubuntu, Debian, CentOS, and Fedora; the README points Arch users to AppImage or tar.gz releases. · github.com, 9 Oct 2026
- Distribution
- The README documents macOS installation through Homebrew and Debian or Ubuntu installation through an APT repository. · github.com, 9 Oct 2026
- Free plan
- Yes · github.com, 20 Sept 2026
- GraphQL support
- Yes · github.com, 20 Sept 2026
- gRPC
- The gRPC client supports unary, server-streaming, client-streaming, and bidirectional streaming, plus .proto imports and server reflection. · github.com, 9 Oct 2026
- gRPC support
- Yes · github.com, 20 Sept 2026
- Intended users
- The README describes Insomnium as a tool for API testing in development and production. · github.com, 9 Oct 2026
- MCP security
- The MCP server is disabled by default, binds to loopback, requires a Bearer token, and uses SSE over HTTP. · github.com, 9 Oct 2026
- Offline use
- The project says the app works 100% offline and has no cloud services, tracking, analytics, or background communication to external servers. · github.com, 9 Oct 2026
- Open source
- Insomnium is open source under the MIT license. · github.com, 9 Oct 2026
- Available platforms
- desktop · github.com, 20 Sept 2026
- Project origin
- Insomnium is a fork of Kong/Insomnia at version 2023.5.8, which the README describes as the last commit before compulsory account login was introduced. · github.com, 9 Oct 2026
- Security maintenance
- The project reports dependency security updates, Electron and native-module refreshes, application security fixes, and CI hardening. · github.com, 9 Oct 2026
- Source build
- The project says users can build Insomnium locally with npm run app-package. · github.com, 9 Oct 2026
- Support and contributions
- The maintainer welcomes issues and pull requests, and the repository provides contributing guidelines and an issue-guidelines link. · github.com, 9 Oct 2026
- WebSocket support
- Yes · github.com, 20 Sept 2026
- What it does
- Insomnium is a local API client for testing GraphQL, REST, WebSockets, server-sent events, and gRPC. · github.com, 9 Oct 2026
Where Insomnium stands on Freedom251
- API clients#17 of 38