spl.js
SpatiaLite 5.1.1-rc0 with SQLite, GEOS, PROJ, and RTTOPO compiled to WebAssembly for Node.js and browser environments.
What is spl.js?
spl.js is a JavaScript library that compiles SpatiaLite and its dependencies (SQLite, GEOS, PROJ, RTTOPO) to WebAssembly, enabling advanced geospatial database operations in Node.js and web browsers. It solves the problem of performing complex spatial analyses, transformations, and queries directly in JavaScript environments without relying on external servers.
Geospatial developers and data scientists who need to perform spatial SQL queries, geometry processing, or coordinate transformations in Node.js applications or client-side web mapping tools.
Developers choose spl.js because it provides the complete SpatiaLite feature set in JavaScript with a unified API, supports multiple geospatial formats natively, and offers extensibility through custom Web Worker extensions, all while maintaining near-native performance.
Overview
SpatiaLite for browser & node
Use Cases
Best For
- Performing spatial SQL queries on GeoPackage files in a web application
- Transforming coordinate systems (e.g., WGS84 to Web Mercator) in Node.js
- Importing and processing zipped Shapefiles directly in the browser
- Creating topologies and simplifying geometries for web mapping
- Running SpatiaLite functions like buffer, intersection, or distance calculations client-side
- Building geospatial data processing pipelines that work both server-side and client-side
Not Ideal For
- Applications requiring real-time, high-performance spatial computations on large datasets, as browser performance is ~50% of native due to WebAssembly overhead
- Firefox-only web applications, due to a known bug with range requests that breaks GitHub Pages examples
- Projects needing extensive PROJ database support out-of-the-box, as the full proj.db requires manual mounting and path configuration
- Simple geospatial tasks like basic GeoJSON manipulation, where lighter libraries like Turf.js are more efficient
Pros & Cons
Pros
Includes SpatiaLite 5.1.1-rc0 with SQLite, GEOS, PROJ, and RTTOPO, enabling advanced operations like topology creation and coordinate transformations directly in JavaScript.
Provides identical synchronous API for Node.js and asynchronous API for browsers via Web Workers, simplifying code reuse across server and client environments.
Automatically handles JSON, GeoJSON, WKB, and supports importing GeoPackage and zipped Shapefiles, as shown in examples loading London boroughs and lights data.
Allows mounting local or remote files (including URLs) for read/write operations, enabling database imports and exports without server dependencies.
Cons
The WebAssembly file is ~4.5MB (~3.4MB gzipped), which can significantly impact initial load times and bandwidth usage in web applications.
Benchmarks show browser performance is ~50% of native SpatiaLite due to WebWorker communication and WebAssembly limitations, affecting compute-intensive tasks.
The default proj.db is minimal; using the full version requires manual mounting and path setting with spatialite functions, adding configuration steps.
Firefox has a known bug with range requests that breaks live examples, limiting cross-browser support without workarounds.
Frequently Asked Questions
Related Projects
Turf.jsA modular geospatial engine written in JavaScript and TypeScript
topoJSONAn extension of GeoJSON that encodes topology! 🌐
geolibZero dependency library to provide some basic geo functions
rbushRBush — a high-performance JavaScript R-tree-based 2D spatial index for points and rectangles
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