Social Media Analysis (Brandwatch, TalkWalker etc.)

I'm trying to build a simplified version of existing software that do social media analysis, such as Brandwatch.

I've seen Mining the Social Web by Matthew Russell being mentioned as a starting point. But this book (and generally what I've seen online) teaches how to get the data from various different platforms.

Question: Are there any platforms/tools/services that provide aggregated data in the form of a Web API?

Note: complete beginner