Salesforce Apex REST vs SOAP APIs

In the ever-evolving Salesforce ecosystem, APIs (Application Programming Interfaces) are the foundation of integrations, automation, and data exchange. Two of the most widely used API frameworks in Salesforce are Apex REST API and Apex SOAP API. While both serve the purpose of connecting Salesforce with external systems, they differ in structure, implementation, performance, and use cases.

This blog will give you a detailed, SEO-friendly comparison of Salesforce Apex REST vs SOAP APIs, helping you decide which is right for your integration needs in 2025 and beyond.

What Are Salesforce Apex APIs?

Salesforce allows developers to expose Apex classes as web services, enabling communication between Salesforce and external systems. These services can be created using RESTful or SOAP-based architectures.

Both APIs provide secure and scalable integration options, but the right choice depends on your use case, data structure, and technical requirements.

Let’s start by understanding each of them in detail.

Understanding Apex REST API

What is Apex REST API?

The Apex REST API is a lightweight, modern, and flexible web service framework based on REST (Representational State Transfer) principles. It uses HTTP methods like GET, POST, PUT, PATCH, and DELETE to perform CRUD (Create, Read, Update, Delete) operations.

Apex REST APIs exchange data using JSON, making them ideal for web, mobile, and cloud-based integrations.

Example of Apex REST API

You can expose an Apex class as a REST service using the @RestResource annotation.

@RestResource(urlMapping='/CustomerAPI/*')
global with sharing class CustomerService {
    @HttpGet
    global static Customer__c getCustomer() {
        RestRequest req = RestContext.request;
        String custId = req.requestURI.substring(req.requestURI.lastIndexOf('/')+1);
        return [SELECT Id, Name, Email__c FROM Customer__c WHERE Id = :custId LIMIT 1];
    }
}

This simple class exposes a REST endpoint that retrieves customer details by ID.

Key Features of Apex REST API

• Lightweight and Fast: Designed for modern applications that require high performance.

• JSON-based Communication: Easy to integrate with web and mobile applications.

• Simple Structure: Uses standard HTTP methods and response codes.

• Flexible Authentication: Supports OAuth 2.0, session ID, and external authentication mechanisms.

• Easy Debugging: Logs and responses are easily trackable.

When to Use Apex REST API

• When integrating Salesforce with mobile or web applications.

• When the external system prefers JSON over XML.

• When you need quick and flexible development for lightweight applications.

• When building microservices or real-time integrations.

Understanding Apex SOAP API

What is Apex SOAP API?

The Apex SOAP API is a robust and structured web service framework that follows the Simple Object Access Protocol (SOAP) standard. SOAP uses XML as the message format and provides strong typing, validation, and WSDL-based communication.

It’s commonly used for enterprise-level integrations where strict message formatting, complex transactions, or formal contracts are required.

Example of Apex SOAP API

You can expose a SOAP web service using the webService keyword and global modifier.

global with sharing class OrderService {
    webService static String createOrder(String orderName, Decimal amount) {
        Order__c order = new Order__c(Name = orderName, Amount__c = amount);
        insert order;
        return 'Order Created: ' + order.Id;
    }
}

After saving the class, Salesforce automatically generates a WSDL (Web Service Definition Language) file, which external systems can use to call this API.

Key Features of Apex SOAP API

• XML-Based Communication: Suitable for enterprise systems that rely on structured data formats.

• Strong Typing: Ensures data integrity with predefined structures and data types.

• WSDL Support: Allows easy integration with legacy systems through standardized definitions.

• High Security: Offers advanced security mechanisms such as WS-Security.

• Transaction Support: Handles complex business logic and bulk operations reliably.

When to Use Apex SOAP API

• When integrating with legacy systems that require SOAP or WSDL.

• When you need strongly typed messages with validation.

• When working in regulated industries that demand strict data compliance.

• When handling complex or transactional data.

Salesforce Apex REST vs SOAP APIs: Key Differences

Advantages of Apex REST API

1. Performance and Scalability: Faster and more efficient for real-time data exchange.

2. Ease of Integration: Works seamlessly with JavaScript, Node.js, Python, and mobile SDKs.

3. Modern Architecture: Ideal for cloud-native and microservice-based integrations.

4. Reduced Overhead: Smaller payloads with JSON compared to verbose XML.

Advantages of Apex SOAP API

1. Enterprise Reliability: Offers strong validation and formal communication contracts.

2. Backward Compatibility: Perfect for systems still using XML or SOAP standards.

3. Structured and Typed Data: Ensures predictable and validated communication.

4. Transactional Capabilities: Better suited for complex business processes involving multiple records.

Which One Should You Choose?

Choosing between Apex REST and SOAP depends on your project’s nature and system requirements.

Choose Apex REST API If:

• You’re building web or mobile applications.

• The integration needs to be lightweight and fast.

• You prefer JSON-based communication.

• You want simple development and quick deployment.

Choose Apex SOAP API If:

• You’re integrating with legacy enterprise systems.

• You require strict message formatting and validation.

• Your use case involves complex transactions or bulk operations.

• Compliance or regulations demand structured XML communication.

Real-World Use Cases

Apex REST API Use Case

A retail company wants to sync customer purchase data between Salesforce and their mobile app. The REST API allows real-time updates and quick responses using JSON, enabling a seamless shopping experience.

Apex SOAP API Use Case

A banking institution integrates Salesforce with its core financial software that uses SOAP-based XML messages for all transactions. The SOAP API ensures data consistency and compliance with banking protocols.

Best Practices for Using Apex APIs

• Always implement authentication (OAuth 2.0 or WS-Security).

• Use proper error handling and return meaningful HTTP or SOAP error codes.

• Log all API requests and responses for auditing.

• Limit data exposure using field-level security and sharing rules.

• Optimize queries and payloads for better performance.

Conclusion

Both Salesforce Apex REST and SOAP APIs are powerful tools for enabling integration between Salesforce and external systems. REST APIs offer speed, simplicity, and flexibility, while SOAP APIs deliver structure, reliability, and security for enterprise applications.

In 2025, as more businesses move toward cloud-native solutions and agile integrations, REST APIs will continue to dominate. However, SOAP remains indispensable for legacy systems and industries with strict compliance requirements.

Ultimately, the best choice depends on your integration goals — if you want speed and modern architecture, choose Apex REST; if you need robustness and formality, go with Apex SOAP.

By mastering both, Salesforce developers can design secure, scalable, and future-ready integration solutions that connect Salesforce seamlessly with any system across the enterprise landscape.