Open-source API proxy
Speed, reliability and observability. Less code.
HARP is an open-source HTTP proxy for your remote APIs, running alongside your applications. It improves the performances, reliability and observability of your internal and external services by instrumenting external HTTP calls.
You focus on delivering your business value, HARP takes care of caching, circuit breaking and recording your API calls.
Get started
One line, and HARP runs
With uv:
uvx harp-proxy server --example sqlite --example proxy:httpbin
With a container:
docker run --init -it --rm -p 4000-4100:4000-4100 makersquad/harp-proxy server
Podman takes the same command: podman run in place of docker run.
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Batteries included!
Comes bundled with the usual API consumer needs
API proxy
Your external API requests and responses go through the proxy, with round-robin pools, fallback pools, connection retries and timeouts.
Read the docsHTTP cache
Responses are cached as RFC 9111 allows, and pattern-based rules can override the upstream's caching policy.
Read the docsDashboard
The dashboard shows aggregated metrics about your transactions: performance, counts and errors, over the last 24 hours or the time range you pick.
Read the docsTraffic history
Transactions are recorded for inspection in the dashboard, with the headers and bodies of requests and responses. Recording is best-effort: under load, HARP sheds detail rather than slowing traffic down.
Read the docsCircuit breaker
Once enabled, it protects your systems from cascading failures by taking failing remotes out of the pool and back in when they recover, using a liveness algorithm and optional health check probes.
Read the docsFlexible storage
From zero-configuration builtin SQLite storage for development to PostgreSQL in production, with an optional Redis content-addressable store for headers and bodies.
Read the docs
You can read the features guide to have an exhaustive glance at HARP's features.
Clean API exchanges
Communications you actually understand
Although we love italian food, we prefer spaghetti not to run on our servers. HARP helps you simplify your service and flux cartography.
- Simple.
- A clear service cartography that anyone can understand.
- Observable.
- One route to rule them all, no headaches looking for the right logs.
- Manageable.
- Adding or removing API-related logic is bound to the target, not each consumer.
- Smart.
- Caching, circuit breaking and transaction recording are builtin, and rules rewrite requests and responses: implemented once, not in each consumer. Don't repeat yourself.
See it in action
The built-in dashboard gives you an at-a-glance overview of your system's health, and a detailed, searchable log of the API transactions it records.
Free and open-source forever.
HARP is free and open-source and will stay so. Get started in minutes, or reach out. Hire the team behind HARP for your API projects: it directly funds HARP and Makersquad's other open-source work. Enterprise support is available too.