We are continuously adding new sources*. The total count has most likely changed as soon as I wrote this sentence.
Our primary source of company-related information are News, Company Websites, Social Handles of Companies, Regulator Websites. On our customer requests, we add custom sources such as Job Portals, Review Websites, Discussion Forums, etc.
NOTE:
We extract strategic updates (link) about companies after removing irrelevant general information noise. It means, we extract only company-related unique information from all the information published on these sources. That's what makes Contify is an intelligence platform -- not just an un-intelligent RSS reader, or a keyword-based alerting system, or a web crawling service.
* We can track all web sources as long as it is legally permissible. E.g. we currently don't track LinkedIn but that might change soon (link).