We migrated 3 SaaS apps off Firebase. Here is when to stay, when to leave, and what to switch to. By David Friedman , Founder of AppBrewers Firebase is the default backend for MVPs. But at 10,000+ users, costs spike and limitations appear. We migrated 3 SaaS apps off Firebase in 2025. Two went to Supabase. One went custom. Here is how to decide. When Firebase Is Perfect Stage Users Firebase Cost Why It Works MVP 0-1,000 0-50 Euro/month Free tier covers everything. Growth 1,000-10,000 50-300 Euro/month Still cheap, still scalable. Scale 10,000-50,000 300-1,500 Euro/month Costs rise but manageable. Enterprise 50,000+ 1,500-5,000 Euro/month Time to evaluate alternatives.…