geojson.io is maintained by the Developer Relations Team at Mapbox. We welcome feature requests, bug reports, and pull requests from the community.
Have a look at our open issues to see if there are bugs or features you are interested in working on. If you need guidance or clarification, you can ask in the issue or check out the discord channel (see below)
There is a geojson-dot-io channel on the MapboxDevs Public Discord Server for general discussion about geojson.io. Feel free to stop by and ask questions or to seek guidance on finding an issue to work on.