What are the limitations of SQLite for large-scale, high-concurrency applications?

SQLite's design choices that make it excellent for embedded, single-application use become real constraints once an application needs many independent processes hammering the same database with heavy concurrent writes.

• Single-writer limitation — only one write transaction can proceed at a time per database file, regardless of how many CPU cores are available.
• No built-in network access — there's no client-server protocol, so remote clients can't connect to it directly the way they would to MySQL/PostgreSQL over a network.
• No user/role-based access control — file-system permissions are the only access control SQLite itself provides.
• Limited horizontal scaling — there's no built-in replication or sharding across multiple database files/servers.

These aren't flaws so much as deliberate tradeoffs for its target use case — a genuinely multi-user, high-write-concurrency backend is exactly the scenario a client-server database like PostgreSQL was built for, and pushing SQLite into that role usually means fighting against its core design rather than working with it.