How do I choose a MERN development company?

Five criteria: (1) Verified third-party reviews with volume, not just score. (2) MERN technical depth (MongoDB aggregation, Atlas Search, Node.js production patterns, Next.js App Router). (3) Operational protections (NDA, IP transfer, replacement clause, ISO 27001). (4) In-house engineers vs subcontracted. (5) Rate relative to seniority and protections delivered. Avoid companies where the price is low but the IP and replacement protections are absent.