There are so many free business tools on the market and the ones you use depends on your business, your customers and your staff. Here are a few recommendations to check out: Evernote to help with taking notes and sharing files, Slack for instant communication, Google Drive for document sharing, Google Analytics for tracking website data and traffic, join.me for video conferencing and Hootsuite for social media management.
Some of these are only free up to a point, but they allow limited access or free trials before you sign your business up to a monthly payment.