The Boundless QGIS plugin brings the functionality of the what3words API to the QGIS platform. You can use the plugin to convert from coordinates to 3 word addresses by adding a field to a shapefile as well as searching for 3 word addresses or inspecting the map to view the 3 word address for a location.
Sign up to get get your free API key.
Download the QGIS plugin from here.
Copy the ‘what3words’ folder to your QGIS plugin folder (this can be found by going to "Settings > User profiles > Open Active Profiles Folder" and opening the "python" folder).
Next, open QGIS, and the what3words plugin will appear under the list of available plugins in the “Manage and Install plugin” tool. Click on the what3words plugin to enable.
Once enabled, you will see what3words under the plugin tab where you can add your API key.
The plugin provides: