Designing for the freemium user model without crashing your database
The freemium business model is great for growth and terrible for backends. Here is how to keep both.
Freemium is the dominant go-to-market for consumer-adjacent SaaS. It is also the fastest way to break a backend nobody designed for free traffic.
The unit-economics problem
Free users do not pay. But they generate reads. A lot of reads. If each free read costs you a database query, you are paying for users who will never pay you. The economics of free-tier reads only work if those reads cost something close to zero.
The redfly answer
Free-tier reads come out of Redis. Paid-tier reads come out of Redis. Writes hit the database. The cache layer is generated, so it is correct without engineering effort. Free traffic stops being a cost center; it becomes a flywheel.
This is not theoretical. We have seen this pattern in production at meaningful scale; including holiday spikes where read volume jumped by an order of magnitude in hours.