With the Bulk Tagger extension you can quickly tag your customers based on their transaction key words.
What are transaction keywords
You’ll be able to tag any transaction with a title using the Bulk Tagger extension.

Once you’ve added the keyword and the tag, you want to tag the customer. Decide whether you actually want to tag or test it to ensure that it’s working OK.
Note that the Bulk Tagger extension is designed for adding tags to contacts based on transaction keywords. It does not support deleting or managing existing tags. To delete tags, use the Tag Manager at Contacts → Tags.