Allows you to redeem your Steam product keys with just one click
Allows you to activate your Steam product keys with only one click.

Install the script
Make sure you have split your Steam keys with comma, like Key1,Key2,Key3
You can paste your keys to Excel in one row, save it as a CSV file, then open the file with Notepad
You can also split them with new line by switching to Multi-line Mode
Go to https://store.steampowered.com/account/registerkey , if it's okay, you'll see a Batch button
Paste your keys to the input field, then click Batch button (NOT Continue button)
Wait until it finishes the work!
The script won't verify the syntax of your keys, you should make it sure by yourself (though Steam will also verify it)
It'll delay about 5 seconds before verifying the next key, to try avoiding banning your request
If it's hard to copy and paste keys one by one, you can try Filter Keys feature to get your keys (see screenshot 3)