We set up a lot of analytics tools for our clients. The most popular is Google Analytics, though it can be a bit hard to use for first time users.
For mobile apps we use Localytics--it’s free for smaller apps. Only if you grow a lot do they start charging. It has a nice interface and covers all the basics.
HubSpot CRM has been helpful; if you type in an email address or company URL, it autofills the other fields for you. You can specify your pipeline, it’s easy to create notes, and it automatically pulls in email conversations with particular leads and clients from your inbox. Also, it’s free.
Sidekick is a HubSpot integration that tracks your emails. You get a notification when someone engages with it. Useful for tracking your sales leads for example.
We used to use Trello, but we switched to Asana. We found it more flexible, powerful, and easy to use. We prefer Asana’s search functionality as well as its UI of ticking a checkmark as opposed to moving a card as you can retain the order more easily.