Every new SaaS faces the same fork: pick an API paradigm, build on it for years. I've shipped production apps with all three in the last 18 months. Here's what actually matters when you're building alone or with a small team. The Quick Answer tRPC : Best for TypeScript monorepos, solo founders, internal APIs REST : Best for public APIs, third-party integrations, multi-client GraphQL : Best for complex data graphs, mobile apps, large teams with dedicated API layer If you're a solo founder building a Next.js SaaS in 2026: tRPC. The DX advantage is too large to ignore. tRPC: End-to-End Types Without the Schema // server/router.ts import { router , publicProcedure , protectedProcedure } from ' ./trpc ' ; import { z } from ' zod/v4 ' ; export const appRouter = router ({ user : router ({ getById : protectedProcedure . input ( z . object ({ id : z . string (). uuid () })) . query ( async ({ input , ctx }) => { return ctx . db . user . findUniqueOrThrow ({ where : { id : input .…