Brands love Twitter. They tweet jokes, they watch what you say about them, and, yes, they reply to your complaints.

And now Twitter is giving brands an even more powerful way to understand you—and reach you—on the platform. The company said today it’s launching an API to give brands instant access to every public tweet ever—more than 500 billion tweets spanning more than nine years.

In practice, this access allows companies to review tweets from past advertising campaigns, customer service responses, or product launches to see what worked and what didn’t.

“This is a big step forward in the journey of deriving useful insights and intelligence from social data,” said Giles Palmer, chief executive of social media marketer Brandwatch. “The dream of mining this data for real-time, in-depth, unbiased insights on a global scale is getting ever closer.”

Before last year, Twitter didn’t have the tech in place to make searching every tweet ever possible. Now brands not only can search for your tweets, but use all your past tweeted thoughts to influence you in the future.