Building a SaaS product involves architecture decisions that are difficult to reverse later. The goal at early stage is to choose patterns that support growth without over-engineering for scale you do not yet need.
Key early decisions
- Multi-tenancy model: Shared database with tenant ID vs separate schemas vs separate databases. Shared with tenant ID is simplest to start.
- Authentication: Build custom auth or use a provider (Auth0, Firebase). Providers reduce initial development time.
- Payment integration: Stripe for international, Razorpay for India. Use the gateway's subscription APIs rather than building billing logic from scratch.
- API design: RESTful APIs with clear versioning support future mobile apps and integrations.
What to defer
- Microservices — a well-structured monolith is fine until you have clear scaling bottlenecks.
- Complex caching layers — optimize when performance data shows it is needed.
- Multi-region deployment — start in one region and expand when user geography demands it.