"Should this be a Flow or Apex?" is one of the most common real-world Salesforce design questions — and getting it wrong in either direction creates real problems (unmaintainable Flows, or unnecessary code that a non-developer can't touch later).
When Flow Is the Right Choice
- The logic is straightforward — field updates, simple conditional branching, sending notifications
- The team needs Admins (not just Developers) to maintain it going forward
- You need something built quickly without a deployment pipeline
- The volume and complexity are modest — well within what declarative tools handle efficiently
Example: "When an Opportunity's Stage changes to Closed Won, update the Account's 'Customer Since' field and send an email to the Account Owner." This is a textbook Record-Triggered Flow use case.
When Apex Is the Right Choice
- The logic is genuinely complex — deeply nested conditionals, complex calculations, or logic that would require an unwieldy number of Flow elements to express
- You need fine-grained control over bulk processing at scale (e.g., processing tens of thousands of records efficiently)
- You're integrating with external systems in ways that need custom HTTP callout handling
- You need re-usable, unit-testable business logic shared across multiple contexts (triggers, batch jobs, APIs)
- Performance is critical and you need precise control that declarative tools don't expose
Example: "Recalculate a complex, multi-factor risk score across a customer's entire order history whenever certain related records change, then trigger different downstream actions based on threshold logic." This kind of layered, computationally complex logic is usually cleaner and more testable in Apex.
A Practical Decision Framework
Ask, in order:
- Can this be expressed clearly in a Flow without becoming unmaintainable? If yes, lean Flow.
- Does this need to run efficiently at real scale (thousands of records) with complex conditional logic? If yes, lean Apex.
- Does this need to be unit-tested and reused across multiple different triggers/contexts? If yes, lean Apex (or an invocable Apex method called from Flow).
- Who needs to maintain this after you're gone — an Admin or a Developer? This alone sometimes settles the decision.
The Hybrid Approach
In real Salesforce orgs, the best solutions often combine both: a Flow handles the overall automation trigger and simple branching, then calls an invocable Apex method for the one piece of genuinely complex logic. This gets you Flow's maintainability for the parts that don't need code, and Apex's power for the parts that do.
Learning to Make This Call Well
This judgment only really develops through building both and seeing where each breaks down. Our Salesforce Admin Training and Salesforce Developer Training courses both cover this decision-making explicitly, not just the mechanics of each tool.