An advanced converter module from GeoJSON to KML. tokml supports a wide range of GeoJSON inputs, and even can translate folder structures into the KML format.
Opening and saving files from a browser is complex, as we've written before. This module simplifies the process, working around tricky browser APIs and inconsistencies. Placemark uses flat-drop-files for its powerful file import methods.
check-geojson is a next-generation GeoJSON linter. Unlike other linting or validation utilities, it has both the ability to flag issues down to the specific line and character that caused an issue, but also a mode that allows partially-valid GeoJSON data to be parsed.
Placemark is a minor financial supporter of open source projects at this stage.