Employee (Self-Service)      Manager (Approval/Team View)      HR Staff (Admin/Operations)      System Admin (Config)

Web Portal (React/Angular)      Mobile App (iOS/Android)

Authentication (OAuth2/SSO)      Authorization (RBAC)      Rate Limiting      Routing

Employee Data, Org Structure

Timesheets, Leave Mgmt

Salary Calc, Tax, Insurance

ATS, Candidate Portal

KPIs, Appraisals, 360 Feedback

LMS, Training Path

PostgreSQL/SQL Server

Structured Data (Payroll, Employee Records)

S3/Azure Blob

Files (Contracts, CVs, Photos)

MongoDB

Flexible Data (Performance Logs, Activity Stream)

Redis

Session & Frequent Data

Banks (Payroll Payout)

Tax/Gov Portals (Compliance)

Job Boards (LinkedIn, Indeed)

ERP/Finance System (General Ledger)