Open Source API Clients Software
API Clients provide a dedicated interface for sending requests to servers and analyzing the resulting responses. These tools allow developers to test REST, GraphQL, gRPC, and WebSocket protocols without writing custom code for every test case. This type of software is for engineers who need to debug endpoints and organize request collections. Self-hosting these apps ensures that sensitive API keys and endpoint URLs remain on local hardware. This approach enables version control of request histories through Git instead of relying on external cloud storage.
This page lists 15 open source tools in the API Clients category. The most popular are Hoppscotch, Bruno and Insomnia. Most use the MIT or Apache-2.0 license, and 7 offer an official Docker image.
Hoppscotch
Test, debug, and document APIs using a lightweight client that supports multiple protocols and team collaboration.
Bruno
An offline API client that stores collections on the local filesystem for version control via Git.
Insomnia
A cross platform API client for debugging, designing, and testing REST, GraphQL, gRPC, and WebSocket protocols.
Yaak
A privacy-first desktop API client supporting REST, GraphQL, gRPC, and WebSockets with local-only data storage and Git integration.
Scalar
Generates interactive API documentation and provides an offline first client for testing OpenAPI and Swagger specifications.
massCode
A local first developer workspace combining code snippets, markdown notes, and an integrated HTTP client.
Requestly
Build and test REST and GraphQL APIs with local storage and Git synchronization for developer collaboration.
Reqable
Capture and analyze network traffic while testing REST APIs across desktop and mobile platforms.
RWKV Runner
A management tool for RWKV models that provides an OpenAI compatible API for local LLM execution.
Altair
A GraphQL client IDE for debugging queries and implementations across multiple desktop and browser platforms.
MQTTX
Connect to and test MQTT brokers using a cross-platform client with a chat-like graphical interface.
HTTPie
A command line and desktop client for making HTTP requests and testing REST APIs via terminal.
AntigravityManager
Manage multiple Google Gemini and Claude AI accounts with automated switching and real-time quota monitoring.
Voiden
An offline API workspace that uses plain text files to unify requests, documentation, and tests.
WebHook Tester
Debug and test webhooks and HTTP requests using unique, randomly generated URLs and customizable responses.
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