We of course can’t forget about token entropy. Entropy is a logarithmic measure of information or uncertainty inherent in the possible token combinations. We use it as a representation of uniqueness for a given pattern and it’s important to maintain for the vast number of tokens we generate everyday. For personal access tokens alone, we create over 10k on a slow day and upwards of 18k on peak days. With our new formats, not only did we maintain our previous levels — we increased them!
Source: Behind GitHub’s new authentication token formats | The GitHub Blog