Optional dependencies
---------------------

Highcharts by default is self-contained, but in some situations Highcharts requires external libraries to enable certain features. The following is an overview of these libraries, along with the required license and security information. The loading of the libraries is always configurable in such a way that you can load the files from your own servers if this is a security requirement. Note that even when loading these files, your chart data is never sent to our servers.

|File with source link|License|Loading|Usage
|---|---|---|---|
|[VML-radial-gradient.png](https://code.highcharts.com/gfx/vml-radial-gradient.png)|Highcharts license.|Loaded on demand from [global.VMLRadialGradientURL](https://api.highcharts.com/highcharts/global.VMLRadialGradientURL).|If you are using radial gradients, IE < 9 is unable to render it natively, and needs to load a PNG image pattern. No information from your data is sent across the net, but your page will appear as the referrer in the HTTP request.|
|[svg2pdf.js](https://code.highcharts.com/lib/svg2pdf.js)|MIT. [Open source](https://github.com/yWorks/svg2pdf.js).|Loaded on demand from [exporting.libURL](https://api.highcharts.com/highcharts/exporting.libURL) if not present on page.|Required by the [client side exporting module](https://highcharts.com/docs/export-module/client-side-export) for PDF export.|
|[jspdf.js](https://code.highcharts.com/lib/jspdf.js)|MIT. [Open source](https://github.com/yWorks/jsPDF).|Loaded on demand from [exporting.libURL](https://api.highcharts.com/highcharts/exporting.libURL) if not present on page.|Dependency of svg2pdf, required by the [client side exporting module](https://highcharts.com/docs/export-module/client-side-export) for PDF export.|
|[canvg.js](https://code.highcharts.com/lib/canvg.js)|MIT. [Open source](https://github.com/canvg/canvg).|Loaded on demand from [exporting.libURL](https://api.highcharts.com/highcharts/exporting.libURL) if not present on page.|Required by the [client side exporting module](https://highcharts.com/docs/export-module/client-side-export) to export certain image types in Internet Explorer and pre-Chromium Edge browsers.|
|[rgbColor.js](https://code.highcharts.com/lib/rgbcolor.js)|"Use it if you like it", also available under MIT. [Open source](https://github.com/canvg/canvg/blob/master/rgbcolor.js).|Loaded on demand from [exporting.libURL](https://api.highcharts.com/highcharts/exporting.libURL) if not present on page.|Dependency of CanVG and svg2pdf, required by the [client side exporting module](https://highcharts.com/docs/export-module/client-side-export) for PDF export.|
|[proj4.js](http://proj4js.org/)|MIT. [Open source](https://github.com/proj4js/proj4js).|Not loaded automatically, must be included on page.|Required for [latitude/longitude](https://highcharts.com/docs/maps/latlon) support in Highcharts Maps.|
