For document storage, Durable Objects is amazing: * https://developers.cloudflare.com/workers/runtime-apis/durab... * https://blog.cloudflare.com/durable-objects-easy-fast-correc...
For relational data, there's now D1 (open beta): * https://developers.cloudflare.com/d1/
For bulk storage, there's R2: * https://developers.cloudflare.com/r2/