Forward HTTP API proxy

HARP's primary topology is an HTTP forward proxy. It sits between your application and the external APIs it calls (or internal but separate services), so you can intercept, cache, observe and modify HTTP requests and responses without changing application code.

What is a forward proxy?

A forward proxy is a server that acts as an intermediary between a client and external servers, forwarding the client's requests. With HARP, your application is the client, and the external servers are the APIs you consume. HARP runs inside your own infrastructure and adds caching, resilience and observability on top of those calls.

Topology

HARP is installed on your servers, next to the services that consume it. By intermediating every API transaction initiated by your application, you gain detailed control and observability over what happens. When a third-party API misbehaves, you have the information needed to react quickly, mitigate the impact on your end-user-facing application, and collaborate to fix the root cause.

Running a forward proxy in front of external APIs also keeps reliability logic out of your application code. You get a RFC-9111 compliant cache layer you can tune to your needs, a rules engine to adjust requests and responses, plus circuit breaking, retry-on-failure, remote and fallback pools, and built-in observability.