Pingora is a production-grade Rust framework for building fast, reliable, and programmable networked systems, developed and battle-tested at Cloudflare (handling 40M+ requests/second). It provides a modular architecture with crates for HTTP/1.1 and HTTP/2 proxying, TLS termination (OpenSSL, BoringSSL, rustls, s2n-tls), load balancing (weighted round-robin, consistent hashing), caching (LRU, TinyUFO), rate limiting, and observability (Prometheus, Sentry). The core abstraction is the `ProxyHttp` trait, which allows users to define request/response filters, upstream selection, error handling, and module integration via lifecycle hooks. The framework also includes a server lifecycle manager with graceful shutdown, daemonization, and file descriptor transfer for zero-downtime upgrades. The architecture is library-oriented: users compose services by implementing traits and configuring YAML-based server settings. Key entry points include `pingora::Server` for process management, `pingora_proxy::http_proxy_service` for creating proxy services, and `pingora_load_balancing::LoadBalancer` for background health checks and discovery. Data flows involve downstream HTTP sessions (H1/H2), upstream connections via pooled connectors, and optional caching layers with eviction policies. External dependencies include tokio, http, h2, lru, ahash, and various TLS libraries. While primarily an application framework, Pingora contains research-grade components like `tinyufo` (a lock-free cache algorithm with TinyLFU admission and S3-FIFO eviction) and `pingora-ketama` (nginx-compatible consistent hashing). These are packaged as reusable crates with extensive benchmarks and memory profiling. The codebase is well-structured with clean trait-based abstractions, but the large workspace (20+ crates) and multiple TLS backends introduce maintenance complexity. Overall, it is a high-quality, actively maintained framework suitable for building custom proxies, load balancers, and edge services.