Connectors to every source system your report draws from: direct database queries (PostgreSQL, MySQL, SQL Server, BigQuery) with connection pooling and read-replica routing to avoid adding load to production write replicas, ERP API calls (SAP RFC/BAPI, NetSuite SuiteQL, Dynamics OData), CRM data pulls (Salesforce SOQL with bulk query for large datasets, HubSpot API), SaaS platform exports (Google Analytics 4 Data API, Stripe Sigma/API, Xero Reports API), and file-based ingestion for legacy systems that export CSV or XML on a schedule (SFTP pickup with SHA-256 file integrity verification). Source data is validated for completeness and consistency before entering the pipeline: expected row counts checked against prior period ranges (a daily revenue feed that typically has 500-2,000 rows and returns 12 rows triggers an alert), required fields verified for null presence, and date range coverage confirmed to catch gaps in time-series data. Alerts fire immediately when a data source returns an error, is unavailable beyond its expected response time, or produces data outside expected volume bounds, so you know about the problem before the report is distributed, not after recipients find the discrepancy.