PGlite — Embeddable Postgres in WebAssembly

Introduction

PGlite packages a real PostgreSQL engine into a WebAssembly build that runs directly in the browser or server-side JavaScript runtimes. It provides full SQL compatibility with Postgres in a lightweight embeddable package, ideal for local-first apps, testing, and prototyping.

What PGlite Does

• Runs a complete PostgreSQL instance in the browser with no server required
• Works in Node.js, Bun, and Deno for server-side embedded use cases
• Supports persistent storage via IndexedDB in the browser or filesystem on the server
• Provides reactive live queries that re-execute when underlying data changes
• Includes extension support for pgvector, PostGIS, and full-text search

Architecture Overview

PGlite compiles the PostgreSQL C source code to WebAssembly using Emscripten. The resulting WASM module runs in any JavaScript environment with a virtual filesystem layer that maps to IndexedDB (browser) or the real filesystem (Node.js). A TypeScript wrapper provides the query API, connection pooling, and the reactive live-query layer built on top of logical replication.

Self-Hosting & Configuration

• Install via npm as a standard JavaScript dependency
• No external PostgreSQL server or Docker container needed
• Configure storage backend (in-memory, IndexedDB, or filesystem) at initialization
• Load extensions like pgvector by importing the corresponding PGlite extension package
• Works in serverless environments including Cloudflare Workers and Vercel Edge Functions

Key Features

• Full PostgreSQL wire protocol compatibility in under 3MB compressed
• Reactive live queries that push updates when data changes
• Extension ecosystem including pgvector for AI embeddings
• Zero-dependency local-first storage for offline-capable applications
• TypeScript-first API with full type inference

Comparison with Similar Tools

• sql.js (SQLite WASM) — SQLite compiled to WASM; simpler but lacks Postgres features like JSONB, window functions, and extensions
• libSQL / Turso — SQLite fork with server sync; different SQL dialect and extension model
• DuckDB WASM — Analytical query engine in WASM; optimized for OLAP, not transactional workloads
• CockroachDB — Distributed Postgres-compatible database; requires server infrastructure
• SurrealDB — Multi-model database with embedded mode; uses its own query language, not standard SQL

FAQ

Q: Is PGlite a full PostgreSQL implementation? A: Yes, PGlite compiles the actual PostgreSQL source code to WebAssembly. It supports the vast majority of PostgreSQL features and SQL syntax.

Q: Can I use PGlite for production applications? A: PGlite is well-suited for local-first apps and embedded use cases. For multi-user server workloads, a traditional PostgreSQL deployment is recommended.

Q: How large is the PGlite WASM bundle? A: The compressed bundle is under 3MB, making it practical for browser-based applications.

Q: Does PGlite support migrations? A: PGlite runs standard PostgreSQL DDL, so any migration tool that generates SQL (Drizzle, Prisma, raw SQL) works with it.

Sources

• https://github.com/electric-sql/pglite
• https://pglite.dev