Zendesk

Business communication platform for channel-based messaging, huddles, workflow automation, and app integrations. Slack is used across internal teams and external partner workflows, with enterprise controls for search, identity, and compliance.

Enterprise customer relationship management platform for sales, service, marketing, analytics, and partner workflows. Salesforce combines configurable business apps, AppExchange extensions, and APIs for customer operations across large organizations.

Open-source employee operations platform for small and midsize businesses. It combines recruiting, employee records, time tracking, internal communication, and one-on-ones in one Laravel application.