Comparison between two modern BaaS services

Convex

Good:

Realtime
Alongside DB, also supports auth, file uploads, server functions, and background tasks
Experience from end to end is very typesafe
Backend is open-source
DB is very strictly validated by the schema
Very extensible

Not good:

No direct database access outside of mutations
- Convex requires queries, mutations, and actions for technical reasons, but not being able to let trusted backends directly access the database is a huge pain sometimes
No built-in support for relationships beyond ID pointers, e.g. cascading deletes, enforced related documents
- This is a design decision, and this exists in the form of the convex-ents third party library, but is not enforced at the DB level
The Convex Auth library only has backend support for Next.js
No v.record() validator (it exists, but it's not a part of the public API for some reason)
No v.unknown() validator, only the very unsafe v.any()

Instant

Good:

Very good onboarding experience
DB queries and updates can be made from anywhere, including the backend
A robust permissions system which makes free database access less scary
Builtin auth support
Builtin app devtools - very cool!
No enforced frontend/backend separation makes it really quick and painless to iterate and add features

Not good:

Type safety is lacking and feels like an afterthought:
- No way to sync your schema type with instant.schema.ts
- instant.perms.ts is untyped
- DB updates are completely untyped
Types in instant.schema.ts are not enforced on the backend; you can insert invalid documents without any warnings or errors