tRPC End-to-End Typesafe APIs

Type-safe remote procedure calls with full client-server type inference. No code generation needed. tRPC excels at:

• Zero API generation — Shared types between client and server; type-safe mutations/queries by default
• Middleware composition — Chain middlewares with unstable_pipe() for authentication, logging, authorization
• Input validation — Zod schema validation with auto-formatted error responses
• Error handling — Domain-specific TRPCError codes mapped to HTTP status automatically
• Vertical Slice pattern — Organize by feature (slice), not layer; each slice owns procedures, schemas, data access

Core patterns: procedures (queries/mutations) in routers, input/output schemas for contracts, middleware for cross-cutting concerns, domain errors with proper codes.

Workflow

When designing tRPC APIs:

1. Define the slice — Which feature? (e.g., invitations, payments, users)
2. Schema first — Input schema with Zod, output schema for response contract
3. Create procedures — Query, mutation, or subscription with .procedure.input().query()
4. Add middleware — Authentication, logging, authorization; chain with unstable_pipe()