gRPC

gRPC is a high-performance remote procedure call framework, originally built at Google, that lets one service call methods on another as if they were local functions. It runs over HTTP/2 and serializes messages with Protocol Buffers — a compact binary format defined in a `.proto` schema — rather than JSON. That schema is the contract: both sides generate typed client and server code from it, so mismatched fields fail at build time instead of in production. For SaaS builders, gRPC shines in internal, service-to-service communication where latency and throughput matter, and it supports bidirectional streaming natively. The trade-off: browsers can't speak raw gRPC without a proxy (gRPC-Web), and binary payloads are harder to inspect than plain REST. A common pattern is gRPC between your own services, with a REST or GraphQL edge for public, third-party consumers. Reach for it when you control both ends and need speed.