Choose an HTTP client
Gluegun and gleam_httpc serve different needs. gleam_httpc provides a small request-and-response API over Erlang/OTP's built-in HTTP client. Gluegun provides typed access to Gun connections, streams, HTTP/2, and WebSockets.
| Need | gleam_httpc |
Gluegun |
|---|---|---|
| Send a usual HTTP request and collect one response | Yes | Yes, with gluegun/client |
| Use an HTTP client included with Erlang/OTP | Yes | No; Gluegun depends on Gun |
| Follow redirects through a configuration option | Yes | Handle redirects in application code |
| Use HTTP/2 | No | Yes |
| Open a WebSocket | No | Yes, over HTTP/1.1 |
| Stream request or response bodies | The Gleam package does not expose streaming | Yes |
| Cancel one request stream | No | Yes |
| Control flow and backpressure | No | Yes |
Receive trailers, 1xx responses, or HTTP/2 push |
No | Yes |
| Manage a persistent connection directly | No | Yes |
Use gleam_httpc for simple requests
Section titled “Use gleam_httpc for simple requests”Choose gleam_httpc when your application sends usual REST or JSON requests, uses HTTP/1.1, and can keep the full response body in memory. Its API accepts a complete URL and returns a complete response. OTP manages the underlying client service.
This model works well for scripts, webhooks, and service-to-service requests that do not need protocol-level control.
Use Gluegun for connections and streams
Section titled “Use Gluegun for connections and streams”Choose Gluegun when your application needs one or more of these features:
- HTTP/2 protocol negotiation and concurrent streams.
- WebSocket connections.
- Incremental request or response bodies.
- Stream cancellation or flow-control updates.
- Long-lived connections to one origin.
- Explicit handling of trailers, informational responses, pushes, or upgrades.
Gluegun requires more lifecycle code. You open a connection, wait for protocol negotiation, start a request or upgrade, and close the connection when you finish. The high-level gluegun/client API handles the usual collected-response case. The lower-level request and message APIs keep Gun's stream events visible.
Test WebSocket servers
Section titled “Test WebSocket servers”An HTTP request client cannot test a WebSocket session. End-to-end tests need a client that can perform the HTTP upgrade and then send and receive WebSocket frames. Gluegun can test the upgrade, application messages, control frames, and disconnect flow without a browser or a Node.js process.
See WebSockets for the Gluegun client API and Basic Requests for collected HTTP responses.