Bulk activate product keys in Steam

The Steam client is the only way to activate a Steam product key, and they only allow you to enter one product key at a time.

With some Humble Bundles, the keys are actually for a package of games, and not given individually, although the current bundle (Humble Bundle with Android 5) does not seem to give keys in this fashion.

You could potentially automate the process with some 3rd party app, although you'd have to be aware that the key authentication process can take a variable amount of time. Also, the games default to being installed immediately, which might not be what you want.

There is no official way to do this, but I wrote a simple script for Mac, that does exactly that: https://github.com/timothybasanov/steamkeysactivator

Script uses AppleScript and could not be ported to Windows or Linux.

For Windows, there's now the Steam Bulk Key Activator, which will read a text file of keys and plug them all in for you. You'd have to copy the keys out of the webpage yourself, but it still saves the tediousness of the Steam aspect of it.