Creating Contractual Service Communication

monday.com engineering team describes how they replaced implicit, 'stringly typed' service contracts with explicit, versioned JSON Schemas across their microservices architecture. Starting with their Reporter Service (handling ~100M daily events), they inferred initial schemas from production payloads using LLMs, iterated until achieving 100% validation rates, and centralized schemas in a Git repository. They auto-generated TypeScript interfaces and Go structs from schemas, wired compatibility checks into CI to catch breaking changes before deployment, and assigned clear ownership per schema. The result was an internal event catalogue, reduced schema-drift incidents, and a foundation for exposing internal event streams as stable public APIs.