What SaaS tools are essential for a B2B startup?

The essential B2B startup stack: CRM (HubSpot Free or Pipedrive), communication (Slack), project management (Asana or Linear), documentation (Notion), email (Google Workspace), accounting (QuickBooks or Xero), payroll (Gusto), and analytics (Mixpanel or Amplitude for product, Plausible or GA4 for web). Start lean — add tools only when a clear pain point justifies the cost. Tool sprawl is a real productivity killer in early-stage companies.