Ethereum scaling solutions comparison – which one for what use case?

Seeing a lot of confusion about when to use which scaling solution, so figured I'd share what I've learned building across different stacks.

Optimistic rollups (Arbitrum, Optimism) are solid for general purpose stuff. Good security, decent costs, but that 7 day withdrawal time is brutal for some use cases.

ZK rollups are faster for finality but more complex to develop on and limited EVM compatibility depending on which one you pick.

App specific rollups are where things get interesting. If you need custom gas logic, specific performance requirements, or want full control over your chain parameters, spinning up your own makes sense. I went with Caldera for this because configuring everything yourself from scratch is a nightmare.

The real question is what are you building? High frequency trading? Go ZK. Gaming with tons of microtransactions? App specific rollup with zero gas. Standard DeFi? Probably fine on a shared optimistic rollup.

Don't overthink it though. You can always migrate later if your needs change. Better to ship on something that works than spend six months debating the perfect architecture.