Build it, break it, see the result

Build a short-link service from parts, press Run, and see whether it shortens, redirects and counts clicks, and whether it keeps doing so when a server, the cache or the click worker dies.

Build a home-feed service from parts, press Run, and see whether it saves posts, opens feeds and delivers every new post to the followers, and whether it keeps doing so when a server, the feed cache or the fan-out worker dies.

Build the back end of a chat app from parts, press Run, and see whether it stores messages, shows who is online and sends an alert to a closed app, and whether it keeps doing so when a connection server, the cache or the alert worker dies.

Build a marketplace search box from parts, press Run, and see whether it returns products, serves suggestions and gets a seller's change into the index, and whether it keeps doing so when an app server, a search node or the indexing worker dies.

Build Safar's ride service from parts, press Run, and see whether it stores where drivers are, finds the ones near a rider, saves trips, and keeps going when an app server, a node of the location map or the trip worker dies.

Build the system behind a ticket drop from parts, press Run, and see whether it can hold seats, show which seats are free and confirm payments when 8,000 requests a second hit it at ten o'clock, and whether it keeps going when an app server, the seat-map cache or the payment worker dies.

Build DalilBot from parts, press Run, and see whether it fetches pages, saves them and sends the links it finds back as new work, and whether it keeps going when a fetcher, the seen-URL memory or the page parsers stop.

Build a video platform from parts, press Run, and see whether videos play and uploads become playable, and whether the service keeps going when a CDN network, an app server or the transcoding workers stop.