I'm using the goo.gl link shortener API in my app to send urls to twitter along with a link. I've been allowing users to submit 119 characters, appending a space, and then the URL because I was under the impression that they were always 19 characters. This should leave me with one to spare.
Unfortunately I've been getting some "tweet is too long" errors and I can't seem to find any documentation about the possible range of goo.gl url lengths. Does anyone know what the max is or know where some reliable documentation on it is?
Twitter now automatically shortens all links by itself, using t.co. Don't do it by yourself.
If you are not using the opt-in features, only links shorter in length than a t.co URL will be wrapped by t.co. All links t.co-length or longer should be considered as t.co's maximum length. For example, if help/configuration reports 20 characters as the maximum length, and a user posts a link that is 125 characters long, it should be considered as 20 characters long instead. If they post a link that is 18 characters long, it's still only 18 characters long.
At the moment short_url_length is equal 22 (https://api.twitter.com/1/help/configuration.json)