Postman is where many teams design, send and test API requests, share collections and run them in CI. The open-source clients below cover the same core loop, and several store collections as plain files so they live in Git next to your code instead of in a vendor's cloud.
Every tool listed is under an OSI-approved licence (MIT, Apache-2.0 or BSD-3-Clause), checked against its repository. Most are desktop or terminal apps rather than servers, so the hosting column mostly tells you whether a self-hosted team option exists. Trade-offs, such as paid tiers for some collaboration features, are noted per tool.
Licences checked against each repository on November 7, 2026.
1. Bruno
MITBest for: Git-friendly collections stored as files
Describes itself as an open-source IDE for exploring and testing APIs. Collections are stored as plain files in a folder using the Bru markup language, and teams collaborate through Git. It is offline-only, with a CLI and Docker images for running collections in CI.
Strengths
- + Collections live in your repo as plain text
- + Desktop apps for Mac, Windows and Linux
- + CLI and Docker images for CI pipelines
Trade-offs
- − Offline-only by design, with no cloud sync planned
- − Some features are part of paid versions
2. Hoppscotch
MITBest for: Browser-based, self-hostable team API workspace
Positions itself as an open-source API development ecosystem and alternative to Postman and Insomnia. Supports REST, GraphQL, WebSocket, Server-Sent Events, Socket.IO and MQTT, with collections, environments and pre-request scripts. Available as a web app, desktop apps, a CLI and a self-hosted deployment.
Strengths
- + Many protocols in one tool
- + Web, desktop and CLI options
- + Self-hosting guide and Docker files in the repo
Trade-offs
- − SSO is labelled an enterprise edition feature
- − Self-hosting adds server maintenance
3. Insomnia
Apache-2.0Best for: A familiar API client with OpenAPI design tools
Describes itself as an open-source, cross-platform API client for GraphQL, REST, WebSockets, SSE and gRPC, with Local, Git and Cloud storage. Includes a native OpenAPI design editor, test suites, a collection runner and the Inso CLI for CI/CD.
Strengths
- + Broad protocol support including gRPC
- + OpenAPI editor and test runner built in
- + Local storage option keeps data on your machine
Trade-offs
- − An account is required for most capabilities
- − Unlimited collaboration, Git Sync and SAML/OIDC login are listed as premium
4. Yaak
MITBest for: Fast, privacy-first desktop client
Describes itself as a fast, privacy-first API client for REST, GraphQL, SSE, WebSocket and gRPC, built with Tauri, Rust and React. Imports from Postman, Insomnia, OpenAPI, Swagger and cURL, and can mirror workspaces to the filesystem for Git.
Strengths
- + Imports from Postman, Insomnia and OpenAPI
- + Secrets stored in the OS keychain
- + States it has no telemetry and no cloud lock-in
Trade-offs
- − Desktop only, no self-hosted server
- − Smaller ecosystem than the best-known clients
5. Posting
Apache-2.0Best for: Terminal-first API client
Describes itself as a powerful HTTP client that lives in your terminal. Requests are stored as YAML files you can version-control, with environments, autocompletion, Python scripts before and after requests, and import from Postman and OpenAPI specs.
Strengths
- + Runs in the terminal with Vim-style keys
- + Requests are version-controllable YAML
- + Imports Postman collections and OpenAPI specs
Trade-offs
- − Terminal UI only
- − HTTP-focused, with no mention of other protocols
6. HTTPie CLI
BSD-3-ClauseBest for: Command-line API testing and scripting
A command-line HTTP client designed for testing, debugging and interacting with APIs and HTTP servers. Offers expressive syntax, colourised output, built-in JSON support, forms and file uploads, persistent sessions and an offline mode.
Strengths
- + Readable one-line requests
- + Built-in JSON support and formatted output
- + Easy to use in shell scripts
Trade-offs
- − No collection manager or GUI
- − Not a team collaboration tool
