A JavaScript library for transforming point coordinates between different coordinate systems and datums.
Proj4js is a JavaScript library that transforms point coordinates from one coordinate reference system to another, including datum transformations. It is a port of the PROJ library, enabling accurate geospatial conversions in web and Node.js applications. The library supports a wide range of projections, grid-based adjustments, and flexible input formats.
Developers working with geospatial data in web mapping applications, GIS tools, or data processing pipelines who need to convert coordinates between different coordinate systems and datums.
Proj4js provides a reliable, battle-tested coordinate transformation library for JavaScript, derived from the industry-standard PROJ. It offers extensive projection support, datum transformations, and grid-based adjustments, making it the go-to solution for accurate geospatial conversions in the browser and Node.js.
JavaScript library to transform coordinates from one coordinate system to another, including datum transformations
Open-Awesome is built by the community, for the community. Submit a project, suggest an awesome list, or help improve the catalog on GitHub.
Supports hundreds of projections via PROJ strings, WKT, and PROJJSON, with predefined EPSG codes like EPSG:4326 and UTM zones, allowing flexible conversions for diverse geospatial workflows.
Includes built-in Helmert transformations for many datums and supports grid-based adjustments (NTv2, GeoTIFF) via external files, enabling high-precision conversions as detailed in the README's nadgrid examples.
Accepts coordinates as arrays [x,y] or objects {x,y}, with optional elevation (z) and measure (m) values, and allows axis order control, making it adaptable to various input formats.
Derived from the industry-standard PROJ library, ensuring robust, battle-tested accuracy for coordinate transformations, which is critical for GIS and mapping applications.
Using high-precision grid adjustments requires managing external files (e.g., NTv2 .gsb or GeoTIFF .tif) and additional libraries like GeoTIFF.js, adding setup overhead and potential dependency issues.
Conversions can introduce floating-point errors, as noted in the README example where inverse projection yields 40.99999999999986 instead of 41, which may affect accuracy-sensitive applications.
Requires understanding of PROJ strings, WKT, and coordinate system concepts, with limited beginner-friendly documentation, making it challenging for developers new to geospatial data.
JavaScript-based transformations may be slower for intensive computations compared to native C/C++ libraries, especially when handling large datasets or complex grid-based adjustments.