HARP Project

An open-source HTTP proxy that sits between applications and remote APIs to improve performance, reliability, and observability of external HTTP calls. It solves the problem of managing API traffic by providing caching, retries, circuit breaking, and audit logging without changing application code. It targets developers and operations teams in organizations of all sizes, from startups to enterprises. It is positioned as a self-hosted, open-source alternative to commercial API gateways, with a focus on simplicity and central policy management.

Key features

• API proxy with round robin pooling
• Retry policy and fallback endpoints
• HTTP caching per RFC9111
• Pattern-based cache policy overrides
• Administration dashboard for transactions
• Audit trail with full headers and body
• Circuit breaker with health checks
• Flexible storage: SQLite, PostgreSQL, MySQL
• Anonymization and pseudonymization rules
• Rules engine for request/response manipulation
• Centralized security policy enforcement
• Header injection and stripping
• Traffic filtering by endpoint and method
• TLS encryption for upstream connections