The SaaS Founder's Guide to Choosing a Database

Key Facts

Direct answer: The direct answer is that for most SaaS, Postgres is the right choice. It is relational (handles structured data), ACID-compliant (ensures data integrity), extensible (JSON, full-text search, geospatial), and has the best managed hosting options (Supabase, Neon, Railway).
The Database Options: Postgres is a relational database that has been the default choice for SaaS for years.
The Recommendation: Start with Postgres: For most SaaS, Postgres is the right choice.
When to Add Redis: Add Redis when you need.

Choosing a database is one of the earliest and most consequential decisions for a SaaS. The wrong choice can lead to performance issues, data integrity problems, and painful migrations. But the database landscape is overwhelming: Postgres, MySQL, SQLite, MongoDB, Redis, DynamoDB — how do you choose? This article is the founder's guide to choosing a database, without over-engineering.

The direct answer is that for most SaaS, Postgres is the right choice. It is relational (handles structured data), ACID-compliant (ensures data integrity), extensible (JSON, full-text search, geospatial), and has the best managed hosting options (Supabase, Neon, Railway). Start with Postgres, and only switch if you have a specific need that Postgres cannot meet. For more on database setup, see our article on fixing DATABASE_URL not set.

The Database Options

PostgreSQL (Postgres)

Postgres is a relational database that has been the default choice for SaaS for years. It is ACID-compliant (transactions are reliable), supports JSON columns (for semi-structured data), has full-text search built in, and has excellent managed hosting (Supabase, Neon, Railway).

Choose Postgres if: You are building a typical SaaS (users, subscriptions, payments, content). This covers 90 percent of SaaS use cases.

Do not choose Postgres if: You need horizontal scaling beyond what a single instance can handle (rare for early-stage SaaS), or you need a specific feature that Postgres does not have (rare).

MySQL

MySQL is another relational database, similar to Postgres. It is slightly faster for read-heavy workloads but has fewer features (no JSON columns as flexible as Postgres, weaker full-text search).

Choose MySQL if: You are already using MySQL (e.g., your existing codebase uses MySQL), or you are using a framework that defaults to MySQL (e.g., Laravel).

Do not choose MySQL if: You are starting from scratch. Postgres is a better default.

SQLite

SQLite is a file-based database (no server). It is embedded in the app, which means no network overhead and no connection management. But it does not support concurrent writes well (only one writer at a time), which makes it unsuitable for production SaaS with multiple users.

Choose SQLite if: You are building a local-only app (e.g., a desktop app), or you need a database for testing.

Do not choose SQLite if: You are building a production SaaS with multiple concurrent users.

NoSQL (MongoDB, DynamoDB)

NoSQL databases store data as documents (not rows), which is flexible (no schema) but sacrifices data integrity (no ACID transactions by default). NoSQL is good for unstructured data (e.g., logs, events) but bad for structured data (e.g., users, payments).

Choose NoSQL if: Your data is inherently unstructured (e.g., a CMS where each document has different fields), or you need horizontal scaling that relational databases cannot provide.

Do not choose NoSQL if: You are building a typical SaaS (users, subscriptions, payments). Relational databases (Postgres) are better for structured data with relationships.

Redis

Redis is an in-memory key-value store, not a primary database. It is used for caching, session storage, and job queues. It is extremely fast (sub-millisecond reads) but volatile (data is lost on restart unless persistence is enabled).

Choose Redis if: You need caching, session storage, or a job queue backend. For more, see our article on the SaaS founder's guide to background jobs.

Do not choose Redis as your primary database. It is not designed for persistent storage of critical data.

The Recommendation: Start with Postgres

For most SaaS, Postgres is the right choice:

Relational. SaaS data is relational (users have subscriptions, subscriptions have payments, payments have invoices). Postgres handles relationships naturally.
ACID-compliant. Transactions ensure data integrity (e.g., a payment and the subscription update happen atomically).
JSON support. If you need semi-structured data (e.g., user metadata), Postgres supports JSON columns.
Managed hosting. Supabase (free tier), Neon (free tier), and Railway offer managed Postgres with automated backups, point-in-time recovery, and scaling.
ORM support. Prisma (Node.js), SQLAlchemy (Python), and GORM (Go) all support Postgres natively.

The Setup

Provision a managed Postgres. Use Supabase (free tier: 500MB), Neon (free tier: 3GB), or Railway ($5/month).
Get the connection string. It looks like postgresql://user:password@host:5432/dbname.
Set it as `DATABASE_URL`. In the Deployxa dashboard, set the DATABASE_URL environment variable.
Choose an ORM. Prisma (Node.js), SQLAlchemy (Python), or GORM (Go). The ORM handles queries, migrations, and type safety.
Run migrations. Create your schema and run migrations (e.g., npx prisma migrate deploy).

For more on database setup, see our article on fixing DATABASE_URL not set.

When to Add Redis

Add Redis when you need:

Caching. Cache database queries, API responses, or computed values to reduce database load.
Session storage. Store user sessions in Redis (faster than database, survives app restarts).
Job queue. Use Redis as the backend for BullMQ (Node.js) or Celery (Python).

Do not add Redis until you need it. For a simple SaaS without caching or background jobs, Postgres alone is sufficient.

Common Pitfalls and Troubleshooting

The first pitfall is over-engineering the database choice. Many founders choose NoSQL or distributed databases because they sound scalable, but for a SaaS with 100-1000 users, a single Postgres instance is more than sufficient. The fix is to start with Postgres and switch only when you have a specific need.

The second pitfall is not using a managed database. Self-hosting a database (on a VPS) means you are responsible for backups, security patches, and scaling. The fix is to use a managed provider (Supabase, Neon).

The third pitfall is not configuring the connection pool. Without a connection pool, the app opens too many connections, which causes outages. The fix is to configure the pool size based on the database's connection limit. For more, see our article on the SaaS founder's guide to database connection pooling.

The fourth pitfall is not testing backups. An untested backup is not a backup. The fix is to test backup restore regularly. For more, see our article on how to rehearse a database restore.

The fifth pitfall is not using an ORM. Writing raw SQL queries is error-prone (SQL injection, typos, missing fields). The fix is to use an ORM (Prisma, SQLAlchemy) that handles queries, migrations, and type safety.

Conclusion: Start Simple, Switch When Needed

For most SaaS, Postgres is the right database. It is relational, ACID-compliant, extensible, and has the best managed hosting. Start with Postgres, add Redis when you need caching or job queues, and switch to a different database only when you have a specific need that Postgres cannot meet. Do not over-engineer the database choice — start simple and switch when the product demands it.

Ready to choose your database? Provision a managed Postgres from Supabase or Neon, set it as DATABASE_URL, and start building. For more, see the production checklist before your SaaS takes its first customer and the SaaS founder's guide to database connection pooling. Explore our free developer tools to speed up your workflow.