Testing Data Streams Just Got A Lot Easier

Testing for streaming APIs, right at your desktop.

Your one-stop shop for sending, monitoring, and testing RESTful, gRPC, GraphQL, Websocket, OpenAPI, WebRTC, Webhooks, and streaming API requests. Now with Stress testing and Mocking!

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. **Currently being optimized for a future release**

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. Developers can now pre-load a written proto document, or write a new proto within the code mirror!

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. **Currently being optimized for a future release**

Advanced Testing Capabilities


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.

Configuration Paradise

OpenAPI 3.1

Make API requests based on a range of provided options that are generated according to specifications defined in a yaml or json-formatted OpenAPI document.


WebRTC Peer to Peer Testing

Test low-latency peer to peer connections with both video and text data transmission with a reliable generated SDP offer, simply paste in your application's SDP answer and streamline innovation to your hearts content.

Type-safe API Integration

tRPC Testing

Utilize tRPC type-safe API technology and make custom query, mutation, and subscription requests to any tRPC server, improving the efficiency and scalability of your tRPC API services.

HTTP and GraphQL Preformance Testing

Stress Testing

Preform stress tests to both HTTP and GraphQL endpoints by sending a user selected number of batched requests per second over a selected period over time to a designated endpoint. The response will show useful metrics sucha as average response times, along with the hit and error rates.

Streamline Frontend Development

Mock Server

The new mock server feature in Swell empowers frontend developers to quickly create, modify, and test endpoints with user-defined responses, enabling seamless collaboration, accelerated development, and efficient testing without reliance on backend teams or hardcoded data.

New, Smooth UI

Built with Material UI

A smoother, more intuitive interface for enhanced user experience. Use a navbar to switch protocols, a smoother workspaces container, and find some extra room to breathe.

export workspaces
swell logo

Get Swell Desktop App

The desktop distribution is suggested for Mac, Linux, Windows and x86_64 users.


Adeeb Bayat


Karol Krzywon


Howard Sun


Michael Underbrink


Carter Sarkela


Aaron Cruz


Jeff Levin


Brooke Sauro


Katya Villano


Nitesh Manem


Kevin Li


Tommy Huynh


Chad DeGange


Alec Derritt


Derek Nyren


Elisa Aigamaua


Jeremy Chen


Nguyen Nguyen


William Murphy


Akeem Smith


Christina Walton


Timmy Zhu


Chris Suzukida


Fred Kim


Jason Huang


Nattie Chan


Tanner Malmedal


Jack Sonoda


Jaden Nguyen


Mihran Baytaryan


David Beame


Alexa Nunes


HyeJin Kim


Michael Smith


Travis Lovis


Evelin Goldin


Alexander Adams


Yale Yng-Wong


Ethan Sclarsky


Genevieve Annable


Drew Pomatti


Sam Pyo


Jay Wall


Kurtis Waterbury


Christopher Pan


Michael Prince


Adrian Uesugui


Jacob Viesselman


Jennifer Wu


Ted Craig


Anthony Wong


John Jongsun Suh


Colin Gibson


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