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sql.js

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What sql.js is

sql.js is a free JavaScript library for creating and querying SQLite databases in a browser. It compiles SQLite to WebAssembly and also includes an asm.js build for older-browser compatibility. Applications can run SQL, prepare statements, bind parameters, and read results; they can also register custom JavaScript functions and aggregate functions for SQL. Existing SQLite files can be imported, and a database can be exported as a JavaScript typed array. The database is held in memory, so changes are not saved automatically. A Web Worker build can move CPU-intensive queries off the main application thread, though its API is more limited. The project includes contributed math and string functions, and release artifacts include WebAssembly, asm.js, debug, and Web Worker builds. It is available for web browsers and Node.js, with examples involving npm, webpack, React, and CDNs. sql.js is MIT licensed. Because the database is loaded into memory, large files can cause out-of-memory errors; a native SQLite binding can work directly with database files instead. BigInt retrieval is supported, but binding BigInt values is not.

Who it suits

sql.js suits developers who want to create or query SQLite databases from JavaScript in browsers or Node.js. It is a fit when an in-memory database model and explicit import or export are appropriate.

What it does well

  • Imports existing SQLite files.
  • Exports databases as JavaScript typed arrays.
  • Supports prepared statements and custom SQL functions.
  • Web Worker build can move intensive queries off the main thread.
  • Free and MIT licensed.

What to know first

  • Changes are not persisted automatically.
  • Large databases can run out of memory.
  • Web Worker API is more limited.
  • BigInt values cannot be bound.

Limits

The database remains in memory and does not persist changes automatically. Loading an entire database can lead to out-of-memory errors, and the Web Worker API is more limited; BigInt binding is unsupported.

Plans

PlanBilled and limitsPrice
sql.jsMIT-licensed JavaScript library; database is held in memory; Web Worker API has a more limited interfaceFree

As sql.js.org lists them, read 7 Oct 2026. The maker's own page has the final word.

Getting started

  1. Open the sql.js website
  2. Install or distribute the library through npm or a listed CDN
  3. Choose a WebAssembly, asm.js, or Web Worker release build
  4. Use the API to create or import an SQLite database
  5. Run SQL, prepare statements, and export the database when needed

Verdict

sql.js provides SQLite functionality in JavaScript with browser and Node.js distribution options. Its in-memory design and partial BigInt support are important constraints to consider for an application.

Questions

Is sql.js free?

Yes. It has a free plan and is MIT licensed.

Which platforms does sql.js support?

It supports web browsers and Node.js, with API, self-hosted, and web platform listings.

Can sql.js import and export databases?

It can import existing SQLite files and export a database as a JavaScript typed array.

Does sql.js save changes automatically?

No. Its database is held in memory, so changes are not persisted automatically.

Can queries run outside the main thread?

A Web Worker build can run CPU-intensive queries off the main application thread, with a more limited API.

Facts from sql.js's own pages

BigInt limit
BigInt support is partial: retrieving BigInt values is supported, but binding BigInt values is not. · github.com, 7 Oct 2026
Custom functions
Applications can register JavaScript functions and custom aggregate functions for use in SQL. · github.com, 7 Oct 2026
Distribution
The project is hosted on npm and publishes release artifacts, including WebAssembly loader and binary files. · github.com, 7 Oct 2026
Documentation
The project provides API documentation for its module, database, statement, and statement iterator. · sql.js.org, 7 Oct 2026
Download
Release artifacts include WebAssembly, asm.js, debug, and Web Worker builds. · github.com, 7 Oct 2026
Extensions
The library includes contributed math and string extension functions. · github.com, 7 Oct 2026
Implementation
It compiles SQLite to WebAssembly and also includes an asm.js build for compatibility with older browsers. · github.com, 7 Oct 2026
Import and export
It can import existing SQLite files and export a database as a JavaScript typed array. · github.com, 7 Oct 2026
In-memory database
The database uses a virtual file stored in memory, so changes do not persist automatically. · github.com, 7 Oct 2026
In-memory storage
The database is held in memory, so changes are not persisted automatically. · github.com, 7 Oct 2026
Integrations
The README shows use with Node.js, npm, webpack, React, and CDNs. · github.com, 7 Oct 2026
License
The project states that sql.js is MIT licensed. · github.com, 7 Oct 2026
Performance limit
The README says a native SQLite binding can work directly with database files and avoid loading the entire database into memory, while sql.js may encounter out-of-memory errors. · github.com, 7 Oct 2026
Purpose
sql.js is a JavaScript library for creating and querying SQLite databases in a browser. · github.com, 7 Oct 2026
SQL API
The API supports running SQL, preparing statements, binding parameters, and reading query results. · github.com, 7 Oct 2026
SQL features
The API supports prepared statements and custom JavaScript functions and aggregate functions in SQL. · github.com, 7 Oct 2026
Technology
It compiles SQLite to WebAssembly and includes an asm.js build for compatibility with older browsers. · github.com, 7 Oct 2026
Web workers
A Web Worker build can run CPU-intensive SQL queries off the main application thread, with a more limited API. · github.com, 7 Oct 2026

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