Every airport with a working data adapter, grouped by country. Pick one to see its live departures and terminal load.
An airport can be added whenever its own departure board is reachable and parseable. Some big hubs are absent because they block datacenter traffic outright, not because nobody wants them. Sources are health-checked every 6 hours, and an airport whose board breaks is taken off the site automatically until it works again — so this list is always what genuinely works right now, and it is also available as JSON at /api/airports.
Tell us which one you are missing and we will look at whether its board can be read. A broken or wrong-looking board is worth reporting here too.