I don't understand what you're saying. I can take any cheap rdbms, put a unique constraint on a column, and make my API return 409 for conflict vs 200 on succes

I don't understand what you're saying. I can take any cheap rdbms, put a unique constraint on a column, and make my API return 409 for conflict vs 200 on success. There's so little code involved that it's embarrassing to charge money for it.