Until fairly recently, most sophisticated software, such as accounting and scientific applications, had to be installed and configured on stand-alone computers. Browser technology has now advanced to the point where extremely complex applications can be written that run on the web. This is even largely true of smart-device applications that make use of a device's camera and various sensors. Here are a few web applications I've developed.
View the positions and orbits of all artifical earth satellites. Check out geosynchronous orbits (e.g. GOES) vs near-earth orbits (e.g. OneWeb). See how the Starlink network is rapidly dominating the population of low orbiting satellites. Track indiviudal satellites on a map.
Pin your favorite hotels, restaurants, roadsite attractions (you name it!) to a map. See shared databases of national parks, NFL stadiums, airports (the list keeps growing!). Search and sort locations by name, distance and other attributes that you create yourself. Share your locations with others.
Watch the orbits of the planets about the sun. Switch to an earth-centric view to understand retrograde motion. See how the orbit of Pluto differs significantly from the orbits of the other planets. Click on a planet to see a simulated close-up view.
Get to know the stars, constellations and deep-sky objects you see in the night sky. See where the planets are. Click on an object for details, including rise and set times. Run the app in a mobile device to automatically orient the sky with the device.
Which parts of the world are in daylight, and which are in darkness? Where is the moon and what phase is it in? Visualise the time of day and see rise and set times for the sun and moon at your favorite locations.