Run SQLite in the Browser with sql.js: A Complete Guide from Install to CRUD

Originally published at recca0120.github.io Have you ever needed to run complex queries on the frontend without spinning up a backend for it? I've run into this a few times — local tooling, offline apps, data analysis pages. Every time, I found myself wishing I could just run SQL directly in the browser. sql.js is the answer. It compiles SQLite's C source code to WebAssembly using Emscripten, so the entire SQLite engine runs inside the browser. No server, no API — SQL executes locally. What sql.js Is and How It Works At its core, sql.js uses the Emscripten toolchain to compile SQLite 3's C code into a .wasm binary. Once the browser loads this Wasm module, you have a full SQLite engine available to call. A few important characteristics to know upfront: In-memory by default : The database lives in memory. A page refresh wipes it. For persistence, you need to serialize the data yourself and store it in IndexedDB or localStorage. Synchronous API, asynchronous init : Loading the Wasm module