Extensions

Extensions let you add interactivity to your Felt map, whether that means enabling viewers to search, measure, or filter your data with pre-built tools like Find, Measure, and Spatial filter, or creating a complete application with Custom extensions. With Extensions, you can transform your map into a purpose-built interactive experience tailored to specific workflows all without writing code.

Custom extensions

Custom extensions let you turn any map into an interactive application without writing any code. Felt AI leverages the JS SDK to generate the tools, panels, and workflows you describe in natural language. Everything happens right in Felt: you can preview, adjust, and save your extension with no extra setup or deployment. When you share your map, your application is live and ready for viewers to use.

How to create a custom extension

• Click Extensions () in the toolbar and select the option for Custom extension

• Once selected the extensions editor opens in a split view:

  • the left side includes the AI prompt area where you describe what you want your custom extension to do, and a code editor that displays the generated code with the option to refine. You can view logs in the Console tab of the prompt area as you test your extension.

  • the right side shows a live preview of your map with your custom extensions

  
• Use the prompt area in the bottom left to interact with Felt AI and describe what you want your extension to do

• Felt AI automatically generates code based on your prompt and you will see the code editor update with the option to refine or edit it directly. Once you make your edits, hit Run to see the updates in the preview map.

• Once you have a working extension, choose the option to Save in the upper right. Your custom extension will appear in your map’s legend, where you can rename or reopen it anytime to make further edits.

Custom Extensions let you go beyond pre-built ones to create complete, purpose-built applications with polished UI components like:

• Buttons: Quick actions viewers can click

• Panels: Sidebars that display summaries, stats, or workflows

• Forms: Inputs for viewers to enter text or select options

• Embedded content: Charts or dashboards from other sites displayed in your panel

Tips

• Extensions run when your map is in View mode. While in Edit mode for your map, extensions are disabled so you can edit your map safely. You can still open the extensions editor at any time to edit your extension.

• The preview shows exactly how your custom extension will work before you save or share it

• View debugging or errors in the Console tab in the prompt area

• UI elements automatically match Felt’s design so everything looks polished and integrated

• Clipboard helpers in the editor let you easily copy your map’s viewport or layer IDs

• The overflow menu in the editor offers helpful options like word wrap, auto-run, and delete

• Viewers won’t see your custom extension until you save it

• If you want to go further, see the Felt SDK API reference for details on everything the SDK can do

Pre-built extensions

Felt includes three pre-built Extensions you can add with just a few clicks.

Find

The Find extension enables map viewers to search locations and layers by entering keywords in the search box.

To add Find:

• Click Extensions in the toolbar

• Give your find tool a title

• Choose whether results include search from all layers, specific layers, or locations (places and addresses).

Measure

The Measure extension provides map viewers with tools to measure distances and areas directly on the map.

To add Measure:

• Click Extensions in the toolbar

• Optionally rename the tool.

• Choose which measurement types to offer map viewers: line, polygon, circle, driving, cycling, walking, or flight great arc.

Spatial filter

The spatial filter component enables viewers to filter layers and export the filtered results by drawing a shape on the map. Selecting a spatial filter shows the number of features filtered, along with details about the size and shape of the filtered region.

To add Spatial Filter:

• Click Extensions in the toolbar

• Optionally rename the tool.

• Choose which shapes viewers can draw (polygon, circle, or both).

• Select which map layers the filter applies to.

To let viewers export filtered results, turn on Export data in your map’s settings. Once the setting is on, a download icon will be available to all logged-in viewers from the spatial filter panel.

• Logged-in viewers can download results as GeoPackage, GeoJSON, or CSV

• Logged-out viewers can filter interactively but cannot download data

Spatial filters work great alongside other components set to “Update based on other filters”. In the image below, the statistic and bar chart components are set to update based on other filters, such that they show risk stats for the spatially-filtered region. Lines and polygons that partially intersect the spatial filter are fully counted in calculated statistics.