As a developer, especially in a professional organization, developing an API is much more than just writing code. There is usually a complete Software Development Life Cycle (SDLC) that developers follow.

Typical API Development Process (Developer POV)

1. Requirement Understanding

First, understand:

• What problem is this API solving?
• Who will consume it (Frontend, Mobile App, Third-party)?
• What are the functional requirements?
• What are the non-functional requirements (performance, security, scalability)?

Example

You receive a requirement:

Create an API to get employee details by EmployeeId.

Questions you should clarify:

• What fields are required?
• Who can access this API?
• What should happen if EmployeeId does not exist?
• Any pagination/filtering needed?

Deliverables

• Requirement understanding notes
• User stories / Jira tickets
• Acceptance criteria

---

2. Technical Analysis & Design

Before coding, analyze:

API Contract

Define:

GET /api/employees/{id}

Response:
{
  "id": 1,
  "name": "Deepak",
  "email": "deepak@test.com"
}

Database Impact

• Existing table?
• New table?
• Stored Procedure required?
• Indexes needed?

Security

• Authentication (JWT, OAuth, Entra ID)
• Authorization (Roles/Permissions)

Deliverables

• API Design
• Request/Response Models
• Sequence Flow
• Database Design

---

3. Task Breakdown

Create subtasks:

Backend

• Create Controller
• Create Service
• Create Repository
• Create DTOs
• Create Validation

Database

• Create Table/SP
• Migration Script

Testing

• Unit Tests
• Integration Tests

---

4. Development

Now start coding.

Typical ASP.NET structure:

Controllers
    EmployeeController

Services
    EmployeeService

Repositories
    EmployeeRepository

Models
DTOs
Validators

Coding Standards

• Follow SOLID Principles
• Proper Exception Handling
• Logging
• Dependency Injection
• Async methods

Example:

public async Task<EmployeeDto> GetEmployeeAsync(int id)
{
    var employee = await _repository.GetByIdAsync(id);

    if(employee == null)
    {
        throw new NotFoundException("Employee not found");
    }

    return _mapper.Map<EmployeeDto>(employee);
}

---

5. Unit Testing

Write tests for business logic.

Example:

[Fact]
public async Task GetEmployee_Should_ReturnEmployee()
{
    // Arrange

    // Act

    // Assert
}

What to Test

✅ Success Cases

✅ Failure Cases

✅ Validation

✅ Exception Scenarios

Coverage Target

Many organizations expect:

70% - 90% code coverage

---

6. Local Testing

Test API locally using:

• Swagger
• Postman
• Bruno
• cURL

Verify:

• Status Codes
• Validation
• Authentication
• Error Handling

Example:

200 OK

400 Bad Request

401 Unauthorized

404 Not Found

500 Internal Server Error

---

7. Documentation

Many developers ignore this, but it is extremely important.

API Documentation

Usually via Swagger/OpenAPI

Include:

• Endpoint
• Request
• Response
• Error Codes
• Authentication

Example:

GET /api/employees/{id}

Description:
Returns employee details.

Response:
200 - Success
404 - Employee not found
401 - Unauthorized

---

8. Code Review (Pull Request)

Before merging:

Create PR/MR.

Reviewers check:

• Code Quality
• Security
• Naming Standards
• Performance
• Reusability
• Unit Tests

Typical checklist:

✅ No hardcoded values

✅ Proper Logging

✅ Exception Handling

✅ Tests Passed

✅ Sonar Issues Fixed

---

9. QA Testing

After development:

Deploy to DEV/UAT environment.

QA team validates:

Functional Testing

Does API work correctly?

Regression Testing

Has existing functionality broken?

Negative Testing

Invalid requests

Security Testing

Authentication & Authorization

---

10. Performance Testing (Optional but Common)

For critical APIs:

Tools:

• JMeter
• k6
• LoadRunner

Check:

Response Time
Throughput
Concurrent Users
CPU Usage
Memory Usage

---

11. Deployment

Typical environments:

Local
 ↓
DEV
 ↓
QA/UAT
 ↓
Staging
 ↓
Production

Deployment usually happens through:

• Azure DevOps Pipelines
• GitHub Actions
• Jenkins

---

12. Production Validation

After release:

Verify:

• API accessible
• Logs healthy
• No errors
• Data correctness

---

13. Monitoring & Support

Monitor using:

• Application Insights
• Splunk
• ELK Stack
• Datadog

Track:

• Exceptions
• Slow APIs
• Failed Requests
• Usage Metrics

---

Real-Life Developer Checklist

Whenever you get an API task:

Requirement

• Understand business requirement
• Clarify edge cases
• Understand security requirements

Design

• Design request/response
• Database analysis
• Define error handling

Development

• Implement API
• Add validation
• Add logging
• Handle exceptions

Testing

• Unit Tests
• Local Testing
• Swagger/Postman Testing

Documentation

• Swagger comments
• API documentation
• Deployment notes

Review

• Create PR
• Resolve review comments
• Pass CI/CD checks

Release

• QA Validation
• UAT Sign-off
• Production Deployment

Post Release

• Monitor logs
• Verify functionality
• Support issues

Simple Workflow Diagram

Requirement
    ↓
Analysis & Design
    ↓
Development
    ↓
Unit Testing
    ↓
Code Review (PR)
    ↓
QA Testing
    ↓
UAT Testing
    ↓
Deployment
    ↓
Production Validation
    ↓
Monitoring & Support

If you're working as an ASP.NET API developer, mastering this end-to-end process is often more valuable for career growth than just learning coding, because senior developers and tech leads are expected to own the entire lifecycle, not just implementation.