Every aircraft transmitting within 150 nautical miles, on a scope that refreshes while you watch. The pins take a small detour on their way here: browser to this site's own WordPress REST API, which fetches the flight data server-side, caches it for fifteen seconds, and hands back a trimmed list. The aggregators do not allow browsers to call them directly, so WordPress is quietly the radar's backend.
Starting over False Bay, Cape Town. Tap Center on me to move the scope to your sky; your position goes to this site's endpoint only to pick the search area, and is not stored.