Do I need read replicas for a typical web app?

Usually, no—not at first.

For a typical web app, a single primary database is often enough until you actually see read pressure that justifies replicas. Read replicas add complexity without helping write performance, and they introduce tradeoffs like:

• Replication lag: reads may be slightly stale
• More operational complexity: failover, routing, monitoring
• Harder debugging: “why don’t I see my last write?”
• Extra cost

When replicas make sense

Read replicas are useful if you have:

• Many more reads than writes
  e.g. dashboards, feeds, catalogs, analytics-style queries
• Slow/reporting queries that you want off the primary
• Geographic distribution needs
• High availability patterns where replicas help with failover
• A database that’s becoming a bottleneck on read load

When they usually don’t

You probably don’t need them if:

• You’re building a new app / MVP
• Your traffic is moderate
• Reads and writes are both well within what one DB can handle
• You mostly want “scalability” but haven’t measured a real bottleneck yet

Better first steps before replicas

Before adding replicas, usually try:

• Add indexes
• Optimize slow queries
• Cache hot data (Redis/memory cache)
• Use pagination
• Move expensive jobs async
• Scale the primary vertically first if needed

Rule of thumb

If you haven’t already measured:

• DB CPU/IO saturation
• high read QPS
• slow queries due to load
• inability to serve traffic from one primary

…then don’t start with replicas.

If you want, I can help you decide based on your stack (Postgres/MySQL, traffic volume, read/write ratio, cloud provider).