How does PGLite run PostgreSQL in the browser?

Compiles PostgreSQL C code to WASM via Emscripten, replaces OS API dependencies with WASM-compatible implementations, uses virtual filesystem (memory/IndexedDB/OPFS), runs in single-process mode.

What are ideal use cases?

Local-First offline apps (full SQL + ElectricSQL sync), unit testing (50ms isolated instances), in-browser AI vector search (pgvector), edge/serverless computing.

What are performance limitations?

Write performance ~1/10 of server (single-process + IndexedDB), complex JOINs 2-3x slower, recommended <500MB per instance.

— AI DAILY

Sources

GitHub
Dev.to