Base62

https://github.com/j0rg/Base62

Working with base 62 can be useful if we work with a 62 characters alphabet like 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ. A common application could be to easily generate short Youtube/Tinyurl-like id from a big base 10 integer.