Internet services sometimes contain easter eggs secretly planted by developers. Google's barrel roll search trick and YouTube's rainbow progress bar are famous examples, but short URL services harbor their own hidden gems.
Bitly has several reserved slugs. While users can freely set custom slugs, certain strings are system-reserved. This list includes not just inappropriate word filters but slugs the Bitly team secured playfully. Accessing `bit.ly/bitly` redirects to Bitly's official site, a slug reserved for their own use rather than user-created.
TinyURL's early version included a preview page option. Accessing `preview.tinyurl.com/{slug}` displayed the redirect destination URL, letting users verify safety before clicking. This feature existed since TinyURL's 2002 launch, making it one of the earliest short URL security measures. While many services now offer preview features, TinyURL's pioneering role is little known. Internet easter egg books are available on Amazon.
Using slugs themselves as messages is an easter egg-like culture. Custom slugs like `tan.be/i-love-you` or `tan.be/happy-birthday` embed messages in URLs. This technique is actually used for proposals and birthday surprises, with Reddit's r/relationships regularly featuring "proposed via short URL" posts.
HTTP status codes also contain easter eggs. HTTP 418 "I'm a teapot" originated from a 1998 April Fools' RFC. Some short URL services return 418 instead of 404 for nonexistent slugs. Google's goo.gl displayed a timeline of its history on the shutdown page, a developer's elegant touch transforming a sad event into gratitude and historical record. Short URL services may appear simple, but they're filled with developer playfulness and love for internet culture.