CockroachDB vs MongoDB Atlas

CockroachDB is a distributed SQL database that speaks the Postgres wire protocol. Your existing Postgres drivers, ORMs, and queries work without changes. The key selling point is resilience — data is automatically replicated across nodes, so a zone going down does not take your database offline. The Serverless free tier gives you 10 GiB of storage and 50 million request units, which covers a moderate production workload.

For most solo founders, CockroachDB is more database than you need. The distributed architecture adds write latency (each write requires consensus across nodes), and you are paying that cost even if your app runs in a single region. Where it makes sense is if you are building something that genuinely needs multi-region availability or you want to avoid ever dealing with database failovers. For simpler use cases, Neon or Supabase give you standard Postgres with less overhead.

MongoDB Atlas is the managed cloud version of MongoDB, the most popular document database. You get a free shared cluster with 512 MB of storage that stays running 24/7 — no pausing for inactivity like some competitors. Documents store as JSON-like objects, so your data structure can evolve without formal migrations. This makes it fast to prototype with.

The tradeoff is well-documented: document databases trade query flexibility for schema flexibility. As your app grows, you may find yourself duplicating data across collections or writing complex aggregation pipelines that would be simple JOINs in SQL. For solo founders, MongoDB works best when your data is naturally document-shaped (CMS content, user profiles, event logs). If your data has lots of relationships, Postgres on Supabase or Neon will save you headaches down the road.