Salesforce API Interview Questions and Answers (2026): Complete Guide

Introduction to Salesforce APIs

Salesforce is a leading customer relationship management (CRM) platform that helps organizations manage customer information, sales activities, service operations, and business processes. To connect Salesforce with external applications, databases, websites, and enterprise systems, developers use Salesforce APIs.
Salesforce API development is an important skill for Salesforce Administrators, Developers, Technical Consultants, and Integration Architects. Interviewers commonly ask questions about REST API, SOAP API, Bulk API, GraphQL API, OAuth authentication, data synchronization, and integration troubleshooting.
This guide covers essential Salesforce API interview questions and answers, practical examples, security concepts, and preparation tips to help beginners and experienced professionals prepare for technical interviews.

Understanding Salesforce APIs

1. What Is Salesforce API?

Salesforce API is a collection of interfaces that allow external applications and services to interact with Salesforce data and functionality. Developers can use APIs to retrieve records, create new records, update existing data, delete records, and integrate Salesforce with other systems.
For example, an e-commerce application might send customer details to Salesforce whenever a customer completes a purchase. A support application could retrieve Salesforce case information and display it in another interface.
Salesforce APIs help organizations automate workflows, synchronize data, and connect different business applications.

2. What Are the Main Types of Salesforce APIs?

Salesforce offers different APIs for different integration requirements.

REST API: Provides resource-based access to Salesforce data using HTTP requests and commonly uses JSON responses.
SOAP API: Provides structured XML-based web service operations and uses a Web Services Description Language (WSDL) contract.
Bulk API 2.0: Supports large-scale data operations, such as importing or exporting many records asynchronously.
GraphQL API: Allows supported Salesforce data to be requested through a GraphQL query, so applications can specify the fields and related data they need.
Pub/Sub API: Supports event-driven integrations using Salesforce platform events and change events.
Metadata API: Supports retrieving, deploying, and managing Salesforce configuration and metadata.
Tooling API: Provides programmatic access to development tools and selected metadata used during application development.
The best API depends on the data volume, integration pattern, supported resources, and whether the requirement involves records, metadata, or events.

3. Why Are Salesforce APIs Important?

Salesforce APIs allow organizations to connect their CRM with business applications without relying entirely on manual data entry. They support automation, reduce duplicated work, and help keep information consistent across systems.
Common use cases include integrating Salesforce with ERP systems, websites, payment platforms, marketing applications, mobile apps, and external reporting tools.

4. What Are the Prerequisites for Learning Salesforce APIs?

To learn Salesforce API development, start with the following concepts:

Salesforce objects, fields, records, and relationships.
Basic HTTP methods, status codes, headers, and request bodies.
JSON and XML data formats.
Authentication and authorization concepts, especially OAuth 2.0.
SOQL for querying Salesforce records.
Basic programming knowledge, such as Apex, Java, JavaScript, or Python.
You do not need to master every programming language before starting. A good understanding of Salesforce data and HTTP fundamentals will make API concepts easier to learn.

Salesforce REST API Interview Questions and Answers

5. What Is Salesforce REST API?

Salesforce REST API is a web service interface that allows applications to access Salesforce resources through HTTP requests. It is commonly used for integrations involving web applications, mobile applications, and external services.
REST API supports operations such as retrieving records, creating records, updating records, deleting records, and executing supported queries.
For example, an application can retrieve an Account record using a request similar to:

GET /services/data/vXX.X/sobjects/Account/ACCOUNT_RECORD_ID
Host: your-domain.my.salesforce.com
Authorization: Bearer ACCESS_TOKEN

Replace vXX.X with an API version supported by your Salesforce organization, and replace the record ID and domain with the correct values. The access token must be obtained through an appropriate authentication flow.

6. What Are the Common HTTP Methods Used in REST API?

HTTP methods describe the operation an application wants to perform.

GET: Retrieves a resource or queries data.
POST: Creates a resource or submits a request for an operation.
PATCH: Updates specified fields of an existing resource.
PUT: Commonly replaces a resource in general REST designs; Salesforce endpoint support and behavior depend on the specific resource.
DELETE: Deletes a supported resource.
The exact method and request format depend on the Salesforce REST resource being used.

7. How Do You Create a Record Using Salesforce REST API?

To create a record, send a POST request to the appropriate sObject endpoint with the field values in the request body.
Example:

POST /services/data/vXX.X/sobjects/Account/
Authorization: Bearer ACCESS_TOKEN
Content-Type: application/json

Request body:

{
  "Name": "Example Technologies",
  "Industry": "Technology"
}

If the request succeeds, Salesforce returns a response containing information such as the new record ID and a success indicator.
The authenticated user must have the required object permissions, field permissions, and access to the relevant functionality.

8. What Is SOQL, and How Is It Used with REST API?

SOQL stands for Salesforce Object Query Language. It retrieves records and fields from Salesforce objects.
Example:

SELECT Id, Name, Industry
FROM Account
WHERE Industry = 'Technology'

You can submit supported SOQL queries through the REST API query resource. The response contains matching records and may include a locator or related information when more results need to be retrieved.
SOQL is similar to SQL in some respects, but it is designed for Salesforce data and has its own syntax and limitations.

9. What Is the Difference Between REST API and SOQL?

REST API is an interface for communicating with Salesforce resources, while SOQL is a query language for retrieving Salesforce data.
For example, REST API provides the HTTP endpoint used to submit a query, and SOQL specifies which records and fields to retrieve. They work together in many integrations.

Salesforce SOAP and Other API Interview Questions

10. What Is Salesforce SOAP API?

Salesforce SOAP API is a web service interface that uses SOAP messages, typically formatted as XML, to exchange information between applications.
It provides defined operations for working with Salesforce records and is often used in enterprise integrations that depend on WSDL-based contracts or existing SOAP clients.
SOAP API can be appropriate when an organization’s architecture already uses SOAP services or when its integration requirements align with Salesforce’s SOAP operations.

11. What Is a WSDL File in Salesforce?

WSDL stands for Web Services Description Language. It describes a web service’s available operations, message formats, and communication requirements.
Salesforce provides WSDL options for different integration scenarios:

Enterprise WSDL: Provides a schema strongly tied to a particular Salesforce organization’s configuration.
Partner WSDL: Provides a more general schema suitable for integrations that work across different Salesforce organizations.
Developers can use a WSDL file to generate client code in supported programming environments, reducing the amount of SOAP message handling they need to write manually.

12. What Is the Difference Between REST API and SOAP API?

REST API and SOAP API both support integration with Salesforce, but they use different approaches.

Feature	REST API	SOAP API
Communication style	Resource-based HTTP requests	SOAP web service operations
Common data format	JSON	XML
Service description	Uses documented REST resources	Uses WSDL
Typical use cases	Web, mobile, and lightweight integrations	Contract-based enterprise integrations
Implementation	Often simpler for web developers	May require SOAP tooling and generated clients
The right choice depends on existing systems, development requirements, and the features supported by the relevant Salesforce API.

13. What Is Salesforce Bulk API 2.0?

Bulk API 2.0 is designed for processing large volumes of records asynchronously. It is useful when an integration needs to import or export many records without making a separate synchronous request for every record.
Typical use cases include migrating customer data, importing product records, updating thousands of Accounts, and exporting data for analytics.
A typical workflow involves creating a job, uploading or identifying the data, closing the job for processing, and checking its results. Developers should also handle failed records, job status, and retry requirements.
Bulk API 2.0 is generally more appropriate for large data loads than making thousands of individual REST requests.

14. What Is Salesforce GraphQL API?

GraphQL is a query language and execution model that allows a client to request specific fields and related data in a single query, where supported.
Salesforce GraphQL API can be useful for applications that need a carefully selected set of Salesforce data without retrieving unnecessary fields.
For example, a client interface might request an Account’s name and selected related Contact information in one supported query.
GraphQL differs from REST because the client describes the desired data shape in its query. However, the available objects, fields, relationships, and operations depend on the Salesforce GraphQL API and its supported capabilities.

15. What Is the Difference Between Bulk API and REST API?

REST API is commonly used for individual records and interactive operations. Bulk API 2.0 is intended for large data operations that run asynchronously.
Use REST API when an application needs to retrieve a customer’s details or update an individual record. Consider Bulk API 2.0 when importing or exporting a large dataset.
Choosing the correct API can improve efficiency and help integrations operate within Salesforce limits.

Salesforce API Authentication, Security, and Error Handling

16. How Does Authentication Work in Salesforce APIs?

Salesforce API integrations commonly use OAuth 2.0 to authorize access. The application follows an appropriate OAuth flow to obtain an access token and includes that token in API requests.
For example:

Authorization: Bearer ACCESS_TOKEN

The authentication flow depends on the type of integration, the application, and whether the process involves a user or a server-to-server connection.
Developers should use supported authentication methods, configure the connected application or external client application as required, and avoid sharing credentials or tokens.

17. What Is OAuth 2.0 in Salesforce?

OAuth 2.0 is an authorization framework that allows applications to obtain limited access to protected resources without collecting a user’s password for every request.
Depending on the scenario, Salesforce integrations may use authorization code flows, client credentials where supported and appropriately configured, or other supported OAuth flows.
The selected flow must match the application’s architecture and Salesforce configuration. Developers should use the current Salesforce documentation when choosing and configuring an authentication method.

18. Are API Keys Enough to Secure Salesforce APIs?

An API key alone is generally not sufficient to authorize access to Salesforce records. Salesforce API access requires an appropriate authentication mechanism and authorization checks.
Secure integrations should use supported OAuth flows, protect secrets, restrict permissions, and store credentials in an appropriate secret manager or platform-supported credential store.
Never hard-code access tokens, client secrets, or passwords in public source code or expose them in browser scripts, logs, or screenshots.

19. How Do You Handle Salesforce API Errors?

API error handling involves examining the HTTP status code and response body, identifying the cause, and applying the correct recovery strategy.
Common examples include:

400 Bad Request: The request may contain invalid fields, malformed data, or an incorrect query.
401 Unauthorized: The request may have a missing, invalid, or expired access token.
403 Forbidden: The authenticated user or application may lack the required permissions.
404 Not Found: The requested resource or record may not exist at the specified endpoint.
429 Too Many Requests: The service may be limiting request frequency.
5xx server errors: A server-side or temporary service issue may require investigation or a controlled retry.
Actual Salesforce responses vary by endpoint and error condition. A good integration records useful diagnostic information without exposing sensitive data, distinguishes permanent errors from temporary failures, and uses bounded retries with backoff when appropriate.

20. What Are Salesforce API Limits?

Salesforce applies API usage limits to help maintain platform reliability and fair resource allocation. The applicable limits depend on factors such as the Salesforce edition, organization usage, API type, and current platform policies.
Developers can monitor API consumption using supported Salesforce tools and response information where available.
To manage API limits effectively:

Use Bulk API 2.0 for appropriate large-scale data operations.
Avoid repeatedly requesting data that can be cached safely.
Retrieve only the fields and records that are needed.
Use pagination or result locators where appropriate.
Monitor API usage and design retry logic carefully.
Review the limits relevant to the organization’s subscription and API type.

21. What Is the Difference Between Synchronous and Asynchronous API Processing?

In synchronous processing, the caller waits for the operation’s response before continuing. This approach is suitable for many interactive requests involving individual records.
In asynchronous processing, the caller submits a job or operation that completes later. The application checks the job status and retrieves the results when available.
Bulk API 2.0 is an example of an asynchronous approach suited to large data volumes. The choice depends on how quickly the result is needed and how much data must be processed.

22. How Can You Call an External API from Apex?

Apex supports outbound HTTP callouts through classes such as Http, HttpRequest, and HttpResponse. A callout allows Salesforce code to communicate with an external service.
A simplified example is:

HttpRequest request = new HttpRequest();
request.setEndpoint('callout:My_Named_Credential/resource');
request.setMethod('GET');

Http http = new Http();
HttpResponse response = http.send(request);

if (response.getStatusCode() == 200) {
    System.debug('Request completed successfully');
} else {
    System.debug('Callout failed: ' + response.getStatusCode());
}

My_Named_Credential is a placeholder for a Named Credential configured in Salesforce. The external service, endpoint path, authentication, and error handling must be configured for the real use case.
For production implementations, handle exceptions, timeouts, response parsing, and unexpected status codes. Use Named Credentials and External Credentials where appropriate instead of hard-coding authentication details.

23. What Is the Difference Between Inbound and Outbound Integrations?

An inbound integration sends a request to Salesforce so an external system can access or modify Salesforce data, subject to authentication and permissions.
An outbound integration sends a request from Salesforce to an external application. This may be implemented through Apex callouts, Flow capabilities, events, or other supported integration mechanisms.
For example, a website sending a new customer record to Salesforce is an inbound integration. Salesforce sending an order notification to an external fulfillment system is an outbound integration.

Practical Salesforce API Interview Scenarios and Career Preparation

24. How Would You Troubleshoot a Salesforce Data Synchronization Issue?

Start by identifying the systems involved, the affected records, and when the issue began. Then check the authentication status, request endpoint, HTTP method, request payload, response status, and error message.
Next, verify field names, data types, required fields, record access, validation rules, and relevant automation. Review logs and API usage information where available.
Once the root cause is identified, correct the issue, retry only the appropriate failed operations, and verify that records are synchronized without creating duplicates. Do not assume authentication is the problem until the evidence supports that conclusion.

25. How Do You Prevent Duplicate Records During API Integration?

Duplicate prevention requires a clear record-matching strategy. Where appropriate, define an External ID field and use Salesforce-supported upsert operations to insert a record when no matching record exists or update an existing matching record.
The integration should use a reliable external identifier, validate incoming data, and handle retries safely. For complex workflows, also consider duplicate rules, matching rules, transaction behavior, and concurrency.

26. What Skills Are Important for a Salesforce API Developer?

A Salesforce API developer should understand:

REST, SOAP, and HTTP fundamentals.
OAuth authentication and API security.
Salesforce objects, relationships, and permissions.
SOQL and Salesforce data structures.
Apex and integration patterns.
JSON, XML, and API testing tools.
Error handling, monitoring, and troubleshooting.
Documentation, communication, and problem-solving.
Practical experience with a small end-to-end integration is especially valuable because it demonstrates how the concepts work together.

27. How Should You Prepare for Salesforce API Interviews?

Begin with REST API fundamentals and practise making authenticated requests to a Salesforce developer environment. Learn to retrieve records, create and update records, execute SOQL queries, and interpret API errors.
Next, study SOAP API, Bulk API 2.0, OAuth flows, API limits, and outbound Apex callouts. Build a small project that synchronizes data between Salesforce and a sample external application.
When answering interview questions, explain not only what an API does but also why you would choose it, how you would secure it, and how you would handle failures.

Learning Resources for Salesforce API Development

Salesforce Trailhead

Trailhead is Salesforce’s official learning platform and provides learning modules, guided projects, and hands-on exercises. It is a useful starting point for Salesforce platform fundamentals, API concepts, and developer skills.

Online Courses and Practice Projects

Online learning platforms can provide structured courses on Salesforce development and integrations. Compare course content, instructor experience, update frequency, practical exercises, and learner reviews before choosing a course.
For practical experience, create a project that retrieves Account records, updates a record through REST API, and handles invalid requests. Extend it later with an asynchronous data load or an outbound Apex callout.

Salesforce API Training at eLearning Solutions

Learners who want structured guidance can explore Salesforce training from eLearning Solutions. Focus on programs that include practical API exercises, integration scenarios, troubleshooting, and interview preparation.
Visit the eLearning Solutions website to explore available training options.

Frequently Asked Questions About Salesforce APIs

1. What is Salesforce API used for?

Salesforce API is used to connect Salesforce with external applications and services. It supports operations such as retrieving records, creating and updating data, bulk processing, querying supported data, and integrating business systems.

2. What is the difference between Salesforce REST API and SOAP API?

REST API uses resource-based HTTP requests and commonly exchanges JSON data. SOAP API uses structured XML messages and a WSDL contract. The appropriate option depends on the integration’s requirements and existing architecture.

3. Which Salesforce API is best for large data volumes?

Bulk API 2.0 is generally suitable for large-scale asynchronous data imports and exports. REST API is often more appropriate for individual records and interactive requests.

4. How do you authenticate Salesforce API requests?

Salesforce API integrations commonly use OAuth 2.0 to obtain an access token. The correct OAuth flow depends on the integration scenario and must be configured with appropriate permissions and security controls.

5. Do I need Apex to work with Salesforce APIs?

No. External applications can call Salesforce APIs using supported HTTP clients and programming languages. Apex is useful when implementing custom business logic or making outbound HTTP callouts from Salesforce.

6. What is the best way to practise Salesforce API interview questions?

Practise in a Salesforce developer environment using an API client and supported authentication flow. Retrieve records, create and update data, test error responses, explore SOQL queries, and build a small integration project.

Conclusion

Salesforce API knowledge is valuable for professionals who want to develop integrations, automate data exchange, and build connected applications. Understanding REST API, SOAP API, Bulk API 2.0, GraphQL API, OAuth authentication, API limits, and error handling can help you prepare for Salesforce developer and integration interviews.
Combine theoretical learning with hands-on projects, follow secure development practices, and use the official Salesforce documentation to verify API-specific behavior and current version details. With consistent practice, you can build the skills needed to troubleshoot integration problems and design reliable Salesforce solutions.