What Is Base62? Why Short Links Look Like That
The 62-symbol alphabet, link #1,788,350,705 becoming 1x1jiD, why base62 is the URL-safe sweet spot, and how Linkly uses base62 codes on linkly.link with random endings on customer domains.
Published September 5, 2026Watch on YouTube →
Transcript
The full spoken transcript, split by chapter.
- 0:00Not keyboard mash
- Ever wondered why short links look like a cat walked across the keyboard? That's not random. That's base sixty two. It's how a huge number hides inside just six characters. And once you see the trick, you can't unsee it. Let me show you.
- 0:15Counting in base62
- Start with how we count. Base ten uses ten symbols. Zero to nine. Base sixty two uses sixty two. The ten digits, twenty six lowercase letters, and twenty six capitals. Same counting rules, bigger alphabet. So numbers get short, fast. Link number one point seven eight billion needs ten digits in base ten. In base sixty two? Six characters. That's the whole trick behind a short link.
- 0:40Why shorteners love it
- Here's why link shorteners love it. Every link lives in a database with a row number. An integer. One, two, three, and so on, forever. Encode that integer in base sixty two, and you get a tiny code that's guaranteed unique. And it only uses letters and numbers. Nothing a URL needs to escape, so the link survives emails, texts, and QR codes. Why not add symbols and go even shorter? Because that's where links start breaking. Base sixty two is the sweet spot. Now, there's a choice to make. Counting in order never repeats itself, but it makes codes guessable. Change one character, find someone else's link. Random codes fix the guessing, but they add a new risk. Collisions. Two random codes can land on the same string, so the system has to check, and try again. Linkly uses both. Base sixty two codes on our linkly dot link domain. Random endings on customer domains. Each trade-off, where it fits best.
- 1:38Encode a number yourself
- Want to play with it? Linkly has a free base sixty two encoder. Paste any number, and watch it shrink. Decode it back, and the number returns. Every short link you've ever clicked has this trick under the hood.
- 1:50A number in disguise
- So that's base sixty two. Not keyboard mash. Just a very big number in a very small disguise. If this was fun, the rest of the channel shows what those little links can actually do. See you in the next one.
