The Apex vs Flow debate is one of the most common questions in the Salesforce community. Salesforce's official stance is "Flow first" — but that is not the complete picture. Here is the honest breakdown from someone who has used both in production for a decade.
The Short Answer
Use Flow when: you need simple-to-moderate automation that admins need to maintain — screen flows, guided processes, basic field updates, record creation, and email alerts.
Use Apex when: you need complex logic, bulk processing that is sensitive to governor limits, transaction control (savepoints or rollbacks), callouts inside triggers, or behavior that Flow cannot express cleanly.
Decision Framework
| Scenario | Use Flow | Use Apex |
|---|---|---|
| Simple field update on record save | ✓ | ✗ |
| Email notification on field change | ✓ | ✗ |
| Complex multi-object logic | Limited | ✓ |
| Bulk data processing (1000+ records) | Carefully | ✓ |
| External API callout | Via Apex Action | ✓ |
| Rollback on error (savepoint) | ✗ | ✓ |
| Admin-maintainable automation | ✓ | ✗ |
| Unit testable logic | Limited | ✓ |
The Real Answer: Use Both
The best Salesforce implementations use both. Flow handles the automation layer that admins maintain; Apex handles the complex logic layer developers own. They complement each other.
A clean pattern: Flow triggers an Apex Action (invocable method) for the heavy logic. Admins update the Flow conditions; developers control the Apex execution. Everyone wins.