Cost Safety: CLI vs API
One bill can ruin a project, and it rarely comes from hosting. It comes from a metered AI . The tools you set up to code with day to day — Claude Code, Cursor, and the like — are usually a flat-rate subscription: the cost of one more is effectively zero. The moment your app calls a raw AI API or SDK — an SDK (Software Development Kit) being the prepackaged code library a provider gives you to call its service — the economics flip: you're billed per , per request, with no ceiling. A buggy retry, an unbounded batch job, or an that loops can quietly turn a $0 idle bill into a four-figure surprise overnight. That's "," and it's the most common way solo builders get burned.
Put a cage around any paid API before it ships:
- Set a hard spend cap in the provider dashboard — a real ceiling, not just an email alert.
- Prefer the flat-rate for development; save the metered API for the production feature that truly needs it.
- Rate-limit your own calls — cap concurrency and requests per minute — and watch the usage dashboard the first few days.
- Use cheap/small models for bulk work, and test on tiny inputs first (one record, not the whole table).
- Never ship an unthrottled loop that calls a paid API. Bound every loop.
Make it a rule from the start: every paid API has a hard cap and a throttle.