D1

D1 is SQLite hosted on Cloudflare’s edge: a real relational database next to your Workers, with almost no setup and very low pricing. For a prototype or hobby project, it really is that easy.

Production is different. Every database has a single writer and a hard size cap, so larger workloads mean manually sharding across databases. At that point you are rebuilding the hard parts of a distributed database on top of a product that does not help you do it. Transient internal errors are also common enough that production calls need retries and alerting.

It sits on Durable Objects storage under the hood, which means it inherits that platform’s operational characteristics too. Great for demos, proofs of concept, and per-tenant toy data. I would not put a production system of record on it today.