Hash generation settings

Incremental hashes begin with zero and increase by one for each new link.

Incremental gives you the shortest possible links

However, it also creates a clear pattern - allowing users to easily guess and try out other short links. if this pattern is a problem then a random hash scheme might be the better choice

Random hashes maintain a fixed length, with all characters changing randomly with each new link.
You can also choose the number of characters to be used. For situations where you want some basic security, you could for example set a long hash length by itself or in combination with upper and lower-case (base62) character set.

Security of short links involves a tradeoff. Perfect security is not an expectation or proper use case for short links. Our service tries to provide the shortest hash code that can prevent collisions and still make them user-friendly. Secure hashes on the other hand require much longer identifiers (possibly 128-256 symbols). User-friendly hashes can't guarantee it. And a really secure hash will not be user-friendly.