WordStream, a company that helps search advertisers choose the best keywords and strategies for their campaigns, has raised $6 million in a second round of funding.

The Boston company launched in January 2009 and said it now powers campaigns for more than 500 businesses. This new round comes from Egan-Managed Capital and Sigma Partners and brings WordStream’s total funding to $10 million.

Here’s how we described WordStream when it launched:

The Boston-based company says that it automatically integrates analytics to prioritize certain keywords, allowing advertisers to make informed decisions at all times. The keywords themselves are continuously chosen based on traffic data, and the software also organizes negative keywords — those that they don’t want their brands associated with. WordStream is offering the product on a monthly subscription basis, charging between $300 and $1,000, dependent on the features, support options and account requirements users choose.

The funding was first reported in TechCrunch prior to WordStream’s official announcement.