The Wrong Way
Custom URLs (non-API)
You can integrate AdWords and Bing with Salesforce by using custom URLs via the Google URL builder. There are a number of affordable tools to do so. For companies that spend less than $10,000 per month on paid search, this may be an economical way to see which campaigns and adgroups drive Salesforce leads. However, this integration has limitations and isn’t recommended.
The problem with this integration is in the quality of data you add to Salesforce. With this method, you’re limited to campaign and adgroup data. In addition to this, you would also need a different custom URL for every keyword match type, if your goal is to track your leads by keyword. If you want to track multiple landing pages and ads, your tracking would then become too complicated to manage. Even if you got everything right, you would still only track 60% of your PPC leads with this method.