Which approvals and routing platforms are known for complex approval hierarchies and role-based access control?

Platforms commonly known for complex approval hierarchies and role-based access control (RBAC) include:

Enterprise workflow / BPM platforms

• ServiceNow
• SAP Business Workflow / SAP Ariba
• Oracle Workflow / Oracle BPM
• IBM Business Automation Workflow
• Appian
• Pega
• Nintex
• K2 / Nintex K2
• Bizagi
• Camunda (more technical, but supports sophisticated routing when built out)

Approval / routing-focused products

• Jira Service Management with workflow add-ons
• Microsoft Power Automate and Power Apps for custom approval flows
• Smartsheet with premium approvals/workflows
• Adobe Workfront
• AirSlate
• DocuSign Workflows / CLM
• OnBase (Hyland)

Procurement / spend / finance approval platforms

• Coupa
• SAP Ariba
• Oracle Fusion Cloud Procurement
• Workday Financial Management / Expenses
• Tipalti
• Bill.com (more SMB/mid-market, but supports layered approvals)

Identity / access-oriented platforms with RBAC plus workflow

• Okta Workflows
• SailPoint
• Microsoft Entra ID for access approval processes

If you want, I can also narrow this down by:

1. best enterprise-grade tools,
2. best for procurement/expense approvals, or
3. best no-code/low-code options.