katipo

Katipo is an HTTP client library for Erlang that lets you make web requests from Erlang applications. Instead of building an HTTP client from scratch, it wraps around two battle-tested C libraries—libcurl (which powers many command-line tools) and libevent (which handles fast event-based networking). The practical benefit is that you get a high-performance, reliable way to fetch data from APIs or talk to web services from your Erlang code.

The core idea is straightforward: you call a function like katipo:post(Url, Options) with a web address and settings, and you get back the response status, headers, body, and any cookies. You can configure things like connection timeouts, whether to follow redirects, custom headers, and SSL certificate verification. Under the hood, libcurl handles the HTTP protocol details (it's been refined over 15+ years), while libevent makes sure your application can handle many simultaneous connections without bogging down.

Katipo would be useful for any Erlang application that needs to call external APIs—say, a backend service that pulls data from a weather API, or a payment system that talks to a gateway. Since the library uses libevent's event loop, it's designed to handle hundreds or thousands of concurrent requests efficiently, which is important if your Erlang application serves many users at once. The README notes the project is still in early alpha, so it's not production-hardened yet, but the approach of standing on the shoulders of libcurl's maturity is sound.

One trade-off worth noting: Katipo ties you to native C code, which means you need to compile it with the right dependencies installed (libcurl and libevent development headers). That adds a deployment step compared to pure Erlang libraries, but buys you the performance and feature completeness of battle-tested C libraries instead of reimplementing HTTP from scratch.