What is Apex? and when to use Apex over Flow?

Posted by Vinay Vernekar 5th January 2026

What is Apex?

Apex is a strongly typed, object-oriented programming language developed by Salesforce. It enables developers to execute flow and transaction control statements on Salesforce servers in conjunction with calls to the API. Apex is used to implement custom business logic that cannot be achieved with declarative tools, and it runs natively on the Salesforce platform with built-in security and multitenant-aware governor limits.

Key characteristics of Apex

  • Platform-native: Runs on Salesforce servers and integrates with Salesforce data and metadata.
  • Object-oriented: Supports classes, interfaces, inheritance, and unit tests.
  • Transaction control: Supports DML, SOQL, SOSL, and commit/rollback behavior within transactions.
  • Governor limits aware: Designed for a multi-tenant environment—developers must write efficient, bulkified code.
  • Asynchronous processing: Supports future methods, Queueable, Batch Apex, and Scheduled Apex.

When to use Apex over Flow

Salesforce offers both declarative automation (Flow) and programmatic automation (Apex). Choose Apex when your requirements exceed the capabilities or maintainability of Flows. Below are practical scenarios and guidelines to help you decide.

Use Apex when:

  • Complex business logic: If logic is highly complex with multiple nested conditions, extensive calculations, or requires sophisticated orchestration, Apex is typically more maintainable and testable.
  • Advanced bulk processing: When processing large data volumes (millions of records) or implementing optimized batch processing patterns, Batch Apex or Queueable Apex gives finer control and performance tuning.
  • Custom integrations and callouts: Apex is required for HTTP callouts to external systems, consuming or exposing custom REST/SOAP APIs, or handling complex authentication flows.
  • Precise transaction control: If you need granular control over save order, partial commits, or custom rollback behavior beyond what flow fault handling provides, Apex is appropriate.
  • Reusable library code: Create utility classes, domain layers, or shared services that encapsulate logic used across multiple triggers, batch jobs, or APIs.
  • Complex error handling and logging: Apex allows rich try/catch, custom exceptions, and structured logging for troubleshooting and monitoring.
  • Event-driven or streaming needs: Implementing complex Platform Event processing, change data capture handlers, or streaming integrations often requires Apex for advanced handling.
  • Governor limits or transaction patterns that Flow cannot handle: Some patterns require granular control over SOQL/DML usage, query optimization, or handling large trigger contexts where Apex bulkification is essential.
  • Packaging and managed packages: If you’re building distribution-ready solutions with encapsulated, upgrade-safe logic, Apex in managed packages provides versioning and protection mechanisms.

Prefer Flow when:

  • Requirements are straightforward (record updates, simple branching, notifications).
  • You want fast delivery by admins or clicks-not-code developers.
  • Auditability and visibility in a visual canvas are important for business stakeholders.
  • No external callouts, no heavy data processing, and logic fits within Flow’s supported elements and limits.

Decision checklist

  • If you need HTTP callouts, custom REST endpoints, or complex asynchronous jobs → Apex.
  • If the logic is short, easy to visualize, and maintainable by admins → Flow.
  • If processing large record sets or needing fine-grain bulk behavior → Apex (Batch or Queueable).
  • If you need strong unit tests and code reuse across packages → Apex.

Example: Simple Apex trigger vs Flow

Below is a minimal Apex example demonstrating bulkified trigger logic to update related records. This pattern is easier to implement reliably in Apex for complex operations and large volumes.

// Bulkified Apex trigger example
trigger OpportunityAmountUpdater on Opportunity (after insert, after update) {
Set acctIds = new Set();
for (Opportunity opp : Trigger.new) {
if (opp.AccountId != null) acctIds.add(opp.AccountId);
}

Map accMap = new Map([
SELECT Id, (SELECT Id, Amount FROM Opportunities WHERE StageName = 'Closed Won')
FROM Account WHERE Id IN :acctIds
]);

List updates = new List();
for (Id accId : accMap.keySet()) {
Decimal total = 0;
for (Opportunity o : accMap.get(accId).Opportunities) total += (o.Amount == null ? 0 : o.Amount);
updates.add(new Account(Id = accId, AnnualRevenue = total));
}

if (!updates.isEmpty()) update updates;
}

While a Flow could handle simple related-record updates, this Apex approach gives explicit control over SOQL, DML, and bulk behavior for high-volume operations.

Best practices when using Apex

  • Always bulkify Apex (handle Trigger.new and collections).
  • Move logic to handler or service classes (trigger frameworks, domain classes).
  • Write comprehensive unit tests with positive/negative and bulk scenarios; aim for >75% coverage for deployments.
  • Apply platform best practices: limit SOQL in loops, use maps/sets, and honor governor limits.
  • Prefer asynchronous Apex for long-running processes (Queueable, Batchable, Scheduled).

Summary: Use Flow for simple, fast-to-build automations and when admins should maintain logic. Use Apex when you need power, precision, scalability, integrations, or maintainable reusable code that exceeds declarative capabilities.