Testing Streams Just Got Easier

Testing for streaming APIs, right at your desktop.

Your one-stop shop for sending, monitoring, and testing RESTful, gRPC, GraphQL, Websocket, and streaming API requests

swell dashboard

All the protocols you'll ever need.

Multiple streams. A single connection.


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. Multiple concurrent streams are allowed for each connection.

Stay connected.

Server-sent Events (SSEs)

Initiated by a simple toggle box, Swell displays SSE events one by one as they come in. Similar to HTTP/2 streams, multiple open connection streams are allowed for SSE.

Keeping in touch

Web Sockets

Swell enables connecting directly to WebSocket servers with an HTTP handshake. Developers can directly send data to the connected WS server in the form of simple strings or binary data. Messages and images are displayed in chatbox format, clearly indicating outgoing and incoming messages.

Queries, Mutations, Subscriptions


Swell includes full support for all three root types of GraphQL — queries, mutations, and subscriptions as well as Introspection - with and without variables. Smart code editor allows for easy query creation.

Bring Your Own Proto (BYOP)


Swell includes full support for all four streaming types of gRPC - unary, client stream, server stream, bidirectional stream.

Built In Test Suite Editor


Compose test suites in JavaScript with built in Chai-style TDD/BDD assertion syntax. Tests will resolve on response data and all results will appear in the new Test Response pane.

Advanced WebSocket Testing

New Features in Swell 0.9

In the latest update to Swell, connect to a Websocket server and test with a variety of data types: binary data (i.e. Binary Large oBjects or array buffers) and strings. Conveniently write mocha/chai assertion tests on data transfers. Further, export data logs as well as measure client/server latency.

swell logo

Get Swell desktop app

The desktop distribution is suggested for Linux, Mac, and Windows users.


Paul Ramirez


Nathan Fleming


Andrea Li


TJ Wetmore




Edward Cho


Jason Liggayu


Miguel Gonzalez


Warren Tait


Nathaniel Adams


Sam Haar


Gary Slootskiy


Robin Yoong


Grace Kim


Alex Sanhueza


Wyatt Bell


John Madrigal


Michael Miller


Grace Spletzer


Hideaki Aomori


Nick Healy


Matt Gin


Stephanie Wood


Kyle Combs


Jason Ou


Anthony Terruso


Brandon Marrero


Kwadwo Asamoah


Abby Chao


Amanda Flink


Kajol Thapa


Billy Tran


Paul Rhee


Sam Parsons


Yoon Choi


Nancy Dao


Evan Grobar


Dan Stein


Amruth Uppaluri