sql-js/sql.js

★ 13,615JavaScriptAudience · developerComplexity · 2/5Setup · easy

Mindmap

mindmap
  root((sql.js))
    What It Does
      SQLite in browser
      WebAssembly runtime
      No server needed
    SQL Features
      Create tables
      Insert and query rows
      Export as binary file
    Limitations
      In-memory only
      No disk persistence
      Use native in Electron
    Use Cases
      Upload and query files
      Client-side data tools
      No-backend prototypes

mindmap root((sql.js)) What It Does SQLite in browser WebAssembly runtime No server needed SQL Features Create tables Insert and query rows Export as binary file Limitations In-memory only No disk persistence Use native in Electron Use Cases Upload and query files Client-side data tools No-backend prototypes

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Things people build with this

USE CASE 1

Let users upload an existing SQLite file and query it directly in their browser without sending any data to your server.

USE CASE 2

Build a browser-based data analysis tool that runs SQL queries on local files with no backend required.

USE CASE 3

Prototype a small web app that needs structured data storage without setting up any database server.

Tech stack

JavaScriptWebAssemblySQLite

Getting it running

Difficulty · easy Time to first run · 30min

Database lives in memory only, all data is lost when the page closes unless you explicitly export and save the binary file.

Open source, specific license terms are not described in the repository explanation.

In plain English

sql.js is a JavaScript library that lets you run a full SQLite database entirely inside a web browser or a Node.js environment, without any server-side component. SQLite is a widely-used database engine that normally stores data in a file on disk, sql.js takes that same code and compiles it to WebAssembly so it can run directly in JavaScript. You can create tables, insert rows, and run queries all within the browser tab. The library is useful when you want to give users a database-powered experience without needing a backend. A typical use case is loading an existing SQLite file that a user uploads, querying it in the browser, and presenting results without any data ever leaving the user's machine. Another common use is prototyping a small app that needs structured data storage. One important limitation to know upfront: sql.js keeps the database in memory rather than writing to disk. When the page is closed or refreshed, the data is gone. If you need the database to persist, you can export it at any time as a file (a binary array) and save or download it yourself. You can also import a previously saved file to pick up where you left off. If you are building a desktop app with a framework like Electron, or working in Node.js where you have access to the filesystem, the README suggests using a native SQLite binding instead. The native version will be faster and can work with database files directly rather than loading everything into memory. The project supports modern browsers through WebAssembly and has a fallback for older browsers that uses a plain JavaScript build. An interactive demo is available online where you can run SQL queries directly in your browser without installing anything.

Copy-paste prompts

Prompt 1

I want to let users upload a SQLite .db file and run SELECT queries on it in the browser using sql.js. Show me the JavaScript code to load the file and execute a query.

Prompt 2

Help me build a browser tool using sql.js that lets users filter rows from an uploaded SQLite database and download the results as a CSV file.

Prompt 3

I'm using sql.js and want the database to survive page reloads. How do I export it as a binary file and reload it on the next visit?

Prompt 4

When should I use sql.js versus a native SQLite binding in Electron or Node.js? Walk me through the trade-offs.

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