Postman

API development and testing platform.

When to Use

• Testing REST APIs
• API documentation
• Automated testing
• Team API collaboration

Quick Start

// GET request with params
// URL: {{baseUrl}}/users?status=active

// POST request body (JSON)
{
  "name": "John Doe",
  "email": "john@example.com"
}

Core Concepts

Environment Variables

// Environments: Development, Staging, Production

// Variables
{
  {
    baseUrl;
  }
} // https://api.example.com
{
  {
    apiKey;
  }
} // your-api-key
{
  {
    userId;
  }
} // 123

// Pre-request Script
pm.environment.set("timestamp", Date.now());

Tests & Assertions

// Response status
pm.test("Status is 200", () => {
  pm.response.to.have.status(200);
});

// Response JSON
pm.test("User has correct email", () => {
  const json = pm.response.json();
  pm.expect(json.email).to.equal("test@example.com");
});

// Response time
pm.test("Response time < 500ms", () => {
  pm.expect(pm.response.responseTime).to.be.below(500);
});

// Save data for next request
const token = pm.response.json().token;
pm.environment.set("authToken", token);

Common Patterns

Authentication

// Pre-request Script for OAuth
const tokenUrl = pm.environment.get("tokenUrl");
const clientId = pm.environment.get("clientId");
const clientSecret = pm.environment.get("clientSecret");

pm.sendRequest(
  {
    url: tokenUrl,
    method: "POST",
    header: {
      "Content-Type": "application/x-www-form-urlencoded",
    },
    body: {
      mode: "urlencoded",
      urlencoded: [
        { key: "grant_type", value: "client_credentials" },
        { key: "client_id", value: clientId },
        { key: "client_secret", value: clientSecret },
      ],
    },
  },
  (err, res) => {
    pm.environment.set("accessToken", res.json().access_token);
  },
);

Collection Runner

// Run collection with Newman (CLI)
npx newman run collection.json \
  -e environment.json \
  --reporters cli,htmlextra \
  --iteration-count 5

Best Practices

Do:

• Use environments for different stages
• Write tests for critical responses
• Version control collections
• Use collection variables

Don’t:

• Hardcode secrets
• Skip response validation
• Create duplicate requests
• Ignore collection organization

Troubleshooting

References

• Postman Documentation
• Newman CLI