Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
EspoCRM - EspoCRM is open source CRM (Customer Relationship Management) software that allows you to see, enter and evaluate all your company relationships regardless of the type.
Knack - Knack is the easiest, most spectacular business management software available.
CiviCRM - A Constituent relationship management for the Civic Sector
Zoho Creator - Zoho Creator is a low-code application development platform that helps you build a custom, mobile-ready apps to run your business.
Less Annoying CRM - A simple customer relationship manager made just for small businesses. Manage contact info, track leads, and never miss a follow-up.