> Instagram uses basic base62 with a very standard alphabet > ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_ This is base64. Base62 would be

> Instagram uses basic base62 with a very standard alphabet > ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_ This is base64. Base62 would be without the "-_" (26 upper case letters + 26 lower case letters + 10 digits = 62, if you include two more characters then it's base64, regardless if the characters are url-safe like -_ or /+ like in the standard base64 encoding). EDIT: Also worth noting that with things like base64/base62/etc. you can either encode a byte array into a string of known characters, or if you deal with integer values only then you can compress it much more by converting from a base10 number to a base62 (or similar) number. For example, "1000" base64 encoded yields "MTAwMA==", but if you'd convert the base10 number 1000 into a base62 number then you'd get "G8". It's like converting between base2 and base10 (binary to dec) or base16 (hex) to base10 (dec).