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Swell: A streaming-focused API development tool
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License: MIT AppVeyor AppVeyor contributions welcome Tweet

Swell is a API development tool that enables developers to test endpoints served over streaming technologies including Server-Sent Events (SSE), WebSockets, HTTP2, and GraphQL.

Getting Started

Visit to download the latest release.

Swell is currently available for OS X, Linux and Windows.


Swell is a one-stop shop for sending and monitoring your API requests

  • Send and monitor requests over HTTP2 (including SSEs), WebSockets, and GraphQL
  • Support for up to six concurrent connections
  • View request/response timing information in an interactive chart
  • Save requests in "collections" of multiple requests
  • Minimize and maximize requests
  • Native OS/X app

Supported Technologies

  • HTTP2: Swell supports full HTTP2 multiplexing of requests and responses. HTTP requests to the same host will be sent over the same connection. Swell will attempt to initiate an HTTP2 connection for all HTTPS requests by default, but will revert to HTTP1.1 for legacy servers.

  • Server-Sent Events (SSE): Swell displays SSE events one by one as they come in.

  • WebSocket (WS): Swell enables connecting directly to WebSocket servers with an HTTP handshake. Developers can directly send messages to the connected WS server. Messages are displayed in chatbox format, clearly indicating outgoing and incoming messages.

  • GraphQL: Swell includes full support for all three root types of GraphQL - queries, mutations, and subscriptions - with and without variables

Additional Features

  • Collections: Swell allows you to save collections for easier testing of multiple requests.

  • Minimize/Expand: Swell allows you to minimize and expand your requests, making it easy to manage everything at once.

Built With

  • Electron
  • React
  • Redux
  • Express
  • Apollo
  • React-Modal
  • IndexedDB
  • Chart.js



This project is licensed under the MIT License

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