Postman Collection API

Overview

A Postman Collection is a structured JSON file that encapsulates a set of pre-configured API requests, including endpoints, HTTP methods (e.g., GET, POST), headers, query parameters, request bodies, and optional scripts for automation or response validation. Postman is a leading tool for API testing, development, and documentation, enabling users to send HTTP requests, inspect responses, manage collections, and automate workflows.

This guide will walk you through every step of the process: installing Postman, importing a sample collection for the JSONPlaceholder API (a free, public API for testing), configuring it, testing requests with detailed request/response examples, and leveraging advanced features. The JSONPlaceholder example is ideal for learning because it requires no authentication and provides predictable responses.

Current Version: As of June, 2025, Postman’s latest version (e.g., v11.50.2) includes enhancements for performance and usability.

Install Postman

Postman is a cross-platform application available for Windows, macOS, and Linux. Installing it is the foundational step for working with API collections.

The process of installation is as follows:

1. Download Postman

Action: Visit the official Postman website athttps://www.postman.com/downloads/.
Explanation: The Postman website provides installers tailored to your operating system (OS). Downloading from the official site ensures a secure, up-to-date version free from malware.
Details:
- The download page auto-detects your OS, and highlights the appropriate download button.
- File types and appropriate sizes:
  - Windows: .exe (~150MB, e.g., Postman-win64-10.24.0-Setup.exe).
  - macOS: .dmg (~150MB, e.g., Postman-osx-10.24.0.dmg).
  - Linux: .tar.gz (~150MB, e.g., Postman-linux-x64-10.24.0.tar.gz) or distribution-specific packages (e.g., .deb for Ubuntu, .rpm).
- Additional considerations:
  - Postman requires internet access for cloud features (e.g., syncing collections) but supports offline mode.
  - For ARM-based devices (e.g., M1/M2 MacBooks), Postman provides native support.
- Why It Matters: Downloading the correct, latest installer ensures compatibility, security, and access to new features, preventing installation or runtime issues.
Fig 01: A screenshot of Postman Downloads

2. Install Postman

Action: Execute the downloaded installer and follow the setup process.
Explanation: Installation copies Postman’s executable files, libraries, and dependencies to your system, configures shortcuts, and integrates with your OS for seamless access. The process is streamlined but varies by platform due to OS-specific conventions. Proper installation ensures Postman runs efficiently and integrates with system features (e.g., desktop notifications, file associations).
Details for Windows OS:
- Locate the .exe file (e.g., C:UsersDownloadsPostman-win64-10.24.0-Setup.exe).
- Double-click to launch the installer. If prompted by User Account Control (UAC), click “Yes” to grant admin privileges.
- The setup wizard opens, presenting:
- License Agreement: Check “I accept the agreement” after reviewing the EULA.
- Installation Path: Default is C:UsersAppDataLocalPostman (~300MB post-installation). Change only if necessary (e.g., to D:\Programs).
- Options: Checkboxes for “Create a desktop shortcut,” “Create a Start menu entry,” and “Add to PATH” (optional for CLI use).
Click “Install” to begin. Installation takes 1–3 minutes, depending on system speed, with a progress bar indicating status.
On completion, click “Finish.” Check “Launch Postman” to open the app immediately.
Postman appears in the Start menu (under “P” or “Postman”) and as a desktop icon (if selected).
Post-Installation Checks:
- Check for updates post-install (Help > Check for Updates in Postman).
Why It Matters: A correct installation ensures Postman is accessible, performs optimally, and integrates with your workflow, avoiding runtime errors or missing features.

Action: Launch Postman and either sign in with an existing account or create a new one.
Explanation: A Postman account enables cloud-based features like syncing collections, environments, and workspaces across devices, accessing shared collections via links, and collaborating in team workspaces. Offline mode is available for local testing but restricts features like importing public collections or using the Postman API Network. Signing in is recommended for a full experience.
Details:
- On first launch, Postman presents a welcome screen with:
- Sign In: For existing users (email/password or SSO).
- Create Account: For new users.
- Work offline or “Skip and go to app” (bottom link, for local use).
Create Account:
- Click “Create Account.”
- Enter:
  - Email (e.g., yourname@example.com).
  - Name (e.g., “John Doe”).
  - Password (8+ characters, strong).
- Alternatively, use single sign-on (SSO) with Google, GitHub, or Microsoft.
- Click “Create Account” and verify your email via a confirmation link (check spam/junk if delayed, ~5 minutes).
- Complete the onboarding wizard:
  - Select role (e.g., “Developer,” “Tester”).
  - Skip team setup or invite colleagues (optional).
  - Choose preferences (e.g., dark/light theme).
Sign In:
- Click “Sign In.”
- Enter email and password or select SSO provider.
- If two-factor authentication (2FA) is enabled, provide the code (via authenticator app or SMS).
Offline Mode:
- Click “Work offline” to bypass login, ideal for quick local testing.
- Limitations: No syncing, no shared links, no team workspaces.
Why It Matters: Signing in unlocks cloud syncing, collaboration, and access to shared resources, streamlining your workflow and ensuring data persistence.

Fig 02: A screenshot of Postman SignIn/SignUp page

4. Verify Installation

Action: Confirm Postman launches correctly and displays its main interface.
Explanation: Verifying the installation ensures the app is fully functional and ready for importing collections. This step identifies issues like missing dependencies, corrupted files, or system incompatibilities before proceeding.
Details:
- Launch Postman (via desktop shortcut, Applications, or terminal).
- The main interface should display:
  - Left Sidebar: Tabs for “Collections,” “APIs,” “Environments,” “History,” “Mock Servers,” and “Flow.”
  - Main Workspace: A central area with a “Create your first request” prompt or a blank request tab.
  - Top Toolbar: Buttons for “New,” “Import,” “Runner,” “Settings,” and a search icon, plus an environment dropdown (default: “No Environment”).
  - Status Bar: Bottom bar showing user status (e.g., “Signed in as yourname@example.com” or “Offline”).
- Test basic functionality:
  - Click “New” > “HTTP Request.”
  - Enter a test URL (e.g., https://postman-echo.com/get) in the URL bar.
  - Click “Send” to verify network connectivity (expect a 200 OK response).
- If Postman fails to launch:
  - Windows: Check Event Viewer (Start > Event Viewer > Windows Logs > Application) for errors like “Missing DLL.”
    - Reinstall Visual C++ Redistributable (vc_redist.x64.exe from Microsoft).
- Why It Matters: A successful launch confirms Postman is ready for importing and testing collections, avoiding delays due to setup issues.

Obtain the Postman Collection

A Postman Collection is a JSON file or shared link containing pre-configured API requests. For this guide, we’ll use JSONPlaceholder, a free, public API for testing, and provide a custom collection.json file to demonstrate the process.

1. Locate the Collection

Action: Identify or create a Postman Collection for the API. https://www.postman.com/downloads/.
Explanation: API providers often supply collections in their documentation to simplify testing by predefining requests, headers, and parameters. JSONPlaceholder doesn’t offer an official collection, so we’ll create a sample one below, which is a common practice for public or undocumented APIs. Collections reduce manual setup and ensure consistency.
Details:
- Check the API’s documentation:
  - For JSONPlaceholder, visit https://jsonplaceholder.typicode.com/ or its GitHub page https://github.com/typicode/jsonplaceholder
  - Look for sections like “Getting Started,” “API Testing,” “Postman,” or “Developer Tools.”
- Common collection sources:
  - Official Documentation: A .json file download link or a “Run in Postman” button (generates a shareable URL).
  - Team/Colleagues: A shared .json file or link via email/Slack.
  - Postman API Network: Public collections at https://www.postman.com/explore (search for “JSONPlaceholder”).
  - Community Forums: Check GitHub, Stack Overflow, or Postman Community https://community.postman.com/.
- If no collection exists:
  - Create one manually:
    - In Postman, click “New” > “Collection,” name it, and add requests.
    - Save as a .json file (right-click > Export).
  - Import an API specification:
    - Use OpenAPI/Swagger files (File > Import > OpenAPI).
    - Convert RAML or WADL to Postman format using Postman’s API tools.
  - Why It Matters: A collection provides a ready-to-use set of requests, minimizing setup errors and accelerating testing.

2. Sample collection.json for JSONPlaceholder

Below is a sample Postman Collection for JSONPlaceholder, designed to test key endpoints for posts and users. Save this code as jsonplaceholder-collection.json on your computer (e.g., C:UsersDownloads or ~/Downloads).

Sample collection.json

{
"info": {
    "_postman_id": "b2c3d4e5-6789-0123-4567-8901abcdef23",
    "name": "JSONPlaceholder API",
    "description": "A comprehensive collection for testing JSONPlaceholder API endpoints, covering posts and users. Includes GET, POST, and query parameter examples.",
    "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
},
"item": [
    {
    "name": "Posts",
    "item": [
        {
        "name": "Get All Posts",
        "request": {
            "method": "GET",
            "header": [],
            "url": {
            "raw": "{{baseUrl}}/posts",
            "host": [
                "{{baseUrl}}"
            ],
            "path": [
                "posts"
            ]
            },
            "description": "Retrieves a list of all posts (100 entries) from JSONPlaceholder."
        },
        "response": []
        },
        {
        "name": "Get Post by ID",
        "request": {
            "method": "GET",
            "header": [],
            "url": {
            "raw": "{{baseUrl}}/posts/1",
            "host": [
                "{{baseUrl}}"
            ],
            "path": [
                "posts",
                "1"
            ]
            },
            "description": "Retrieves a single post with ID 1."
        },
        "response": []
        },
        {
        "name": "Get Posts by User ID",
        "request": {
            "method": "GET",
            "header": [],
            "url": {
            "raw": "{{baseUrl}}/posts?userId=1",
            "host": [
                "{{baseUrl}}"
            ],
            "path": [
                "posts"
            ],
            "query": [
                {
                "key": "userId",
                "value": "1"
                }
            ]
            },
            "description": "Retrieves all posts by user with ID 1 using a query parameter."
        },
        "response": []
        },
        {
        "name": "Create Post",
        "request": {
            "method": "POST",
            "header": [
            {
                "key": "Content-Type",
                "value": "application/json",
                "type": "text"
            }
            ],
            "body": {
            "mode": "raw",
            "raw": "{\"title\":\"Sample Post\",\"body\":\"This is a test post created via Postman\",\"userId\":1}"
            },
            "url": {
            "raw": "{{baseUrl}}/posts",
            "host": [
                "{{baseUrl}}"
            ],
            "path": [
                "posts"
            ]
            },
            "description": "Creates a new post with a JSON payload (mock response)."
        },
        "response": []
        }
    ]
    },
    {
    "name": "Users",
    "item": [
        {
        "name": "Get All Users",
        "request": {
            "method": "GET",
            "header": [],
            "url": {
            "raw": "{{baseUrl}}/users",
            "host": [
                "{{baseUrl}}"
            ],
            "path": [
                "users"
            ]
            },
            "description": "Retrieves a list of all users (10 entries)."
        },
        "response": []
        }
    ]
    }
],
"variable": [
    {
    "key": "baseUrl",
    "value": "https://jsonplaceholder.typicode.com",
    "type": "string",
    "description": "Base URL for JSONPlaceholder API"
    }
]
}

Annotations
- info: Metadata about the collection.
  - _postman_id: Unique identifier (auto-generated by Postman).
  - name: “JSONPlaceholder API” (displayed in the sidebar).
  - description: Explains the collection’s scope (posts and users).
  - schema: Specifies Postman Collection v2.1.0 format for compatibility.
- item: Organized into two folders:
  - Posts: Contains four requests for post-related operations.
    - Get All Posts: GET /posts to retrieve 100 posts.
    - Get Post by ID: GET /posts/1 to retrieve a specific post.
    - Get Posts by User ID: GET /posts?userId=1 to filter posts by user.
    - Create Post: POST /posts with a JSON body to simulate creation.
  - Users: Contains one request.
    - Get All Users: GET /users to retrieve 10 users.
  - Each request includes:
    - name: Descriptive name for the request.
    - method: HTTP method (GET or POST).
    - header: Headers (e.g., Content-Type: application/json for POST).
    - body: JSON payload for POST requests.
    - url: Endpoint with {{baseUrl}} variable and optional query parameters.
    - description: Clarifies the request’s purpose.
  - variable: Defines baseUrl as https://jsonplaceholder.typicode.com, enabling portability across - environments.
  - Purpose: This collection demonstrates common API operations (GET with/without parameters, POST) on JSONPlaceholder’s /posts and /users endpoints, organized into folders for clarity.

3. Understand the Collection

Action: Analyze the collection’s structure and requirements.
Explanation: Understanding the collection’s components (requests, variables, folders) ensures you can configure and use it effectively. The sample collection is straightforward, using one variable (baseUrl) and no authentication, but real-world collections may include scripts, tests, or complex authentication.
Details:
- Structure:
  - Folders: “Posts” and “Users” group related requests for better organization.
  - Requests: For new users.
    - Posts: Four requests covering list retrieval, single item retrieval, filtered retrieval, and creation.
    - Users: One request for list retrieval.
  - Variables: baseUrl is the only variable, resolving to the API’s root URL.
- Requirements:
  - Authentication: None (JSONPlaceholder is public).
  - Dependencies: Internet connection to reach jsonplaceholder.typicode.com.
  - Endpoints: Defined in JSONPlaceholder’s documentation (e.g., /posts, /users.
- Edge Cases:
  - Undefined Variables: If requests use unknown variables (e.g., {{apiKey}}), check the documentation or collection metadata.
  - Deprecated Endpoints: Ensure the collection matches the API’s current version.
  - Rate Limits: JSONPlaceholder has no strict limits, but real APIs may throttle requests (check docs).
- Why It Matters: A clear understanding prevents misconfiguration and helps interpret responses accurately.

Import the Postman Collection

Importing the collection into Postman loads its requests, folders, and variables, making them available for testing.

1. Open Postman

Action: Launch Postman and select or create a workspace.
Explanation: Workspaces are containers for organizing collections, environments, and other Postman resources. The default “My Workspace” is ideal for personal projects, while team workspaces support collaboration. Selecting a workspace ensures your collection is imported to the correct context.
Details:
- Launch Postman via:
  - Windows: Start menu or desktop shortcut.
  - macOS: Applications or Spotlight.
  - Linux: Terminal (/opt/Postman/Postman or desktop shortcut).
- If signed in, Postman loads your default workspace (“My Workspace”).
- If offline, select “Work offline” and use a local workspace.
- To create a new workspace:
  - Click the workspace dropdown (top-left, default: “My Workspace”).
  - Select “Create Workspace.”
  - Enter a name (e.g., “JSONPlaceholder Testing”), set visibility (Personal), and click “Create.”
- Edge Cases:
  - Team Workspaces: Ensure you have “Editor” permissions to import collections (check with workspace admin).
  - Workspace Limit: Free accounts have a workspace limit (typically 3).
  - Sync Issues: If workspaces don’t load, check internet or Postman’s status.https://status.postman.com/
- Why It Matters: Workspaces keep your projects organized and enable seamless collaboration or isolation of personal work.

2. Import the Collection

Action: Import the jsonplaceholder-collection.json file into Postman.
Explanation: Importing parses the collection’s JSON data, creating a new collection with all requests, folders, and variables in your workspace. The sample collection.json above is ready for direct import, simulating a real-world scenario where you download a collection from an API provider.
Details:
- Prepare the collection file:
  - Open a text editor (e.g., Notepad, VS Code, TextEdit).
  - Copy-paste the collection.json code from above.
  - Save as jsonplaceholder-collection.json:
    - Windows: Ensure “Save as type” is “All Files” to avoid .txt extension.
    - macOS: Use “Plain Text” format.
    - Linux: Save with .json extension (e.g., nano jsonplaceholder-collection.json).
  - Example path: C:UsersDownloadsjsonplaceholder-collection.json or ~/Downloads/jsonplaceholder-collection.json.
- Import in Postman:
  - Click Import (top-left, next to “New,” with an upload icon).
  - In the import dialog, select the File tab (default).
  - Click Choose Files (or drag the file into the dialog).
  - Navigate to jsonplaceholder-collection.json, select it, and click Open.
  - Postman previews the collection’s name (“JSONPlaceholder API”).
  - Click Import to add it to your workspace (takes ~1 second).
- Alternative Import Methods:
  - Shared Link:
    - If the collection is shared via a “Run in Postman” URL (e.g., https://www.postman.com/collections/123456789 ), select Link.
    - Paste the URL, click Continue, review the collection, and click Import.
    - Requires sign-in for public/private links.
  - Raw Text:
    - Copy the JSON code from above.
    - Select Raw Text, paste the code, click Continue, and click Import.
    - Useful if you receive JSON via email or text.
  - API Specification:
    - If JSONPlaceholder provided an OpenAPI file, select API and import it to generate a collection.
- Edge Cases:
  - Import Failure:
    - Invalid JSON: Validate the file athttps://jsonlint.com/or check for trailing commas, missing brackets.
    - Wrong Schema: Ensure the collection uses v2.0 or v2.1 (convert older versions in Postman: Tools > Convert).
    - File Corruption: Re-save the file or re-copy the JSON.
    - Permissions: Ensure read access to the file (chmod +r jsonplaceholder-collection.json on Linux).
  - Large Collections: For collections with 100+ requests, import may take ~5 seconds; ensure sufficient RAM.
  - Duplicate Names: If “JSONPlaceholder API” exists, Postman appends a number (e.g., “JSONPlaceholder API (1)”).
- Why It Matters: Importing the collection makes its requests and settings available, enabling configuration and testing without manual setup.

3. Verify Import

Action: Confirm the collection appears in Postman’s sidebar.
Explanation: Verifying ensures the collection imported successfully and is accessible for - configuration. This step catches import errors (e.g., corrupted files, schema mismatches) early.
Details:
- After importing, “JSONPlaceholder API” appears in the Collections tab (left sidebar).
- Expand the collection to view:
  - Two folders: “Posts” and “Users.”
  - “Posts” contains four requests: “Get All Posts,” “Get Post by ID,” “Get Posts by User ID,” “Create Post.”
  - “Users” contains one request: “Get All Users.”
- Click a request (e.g., “Get All Posts”) to open it in a new tab and verify:
  - Method: GET
  - URL: {{baseUrl}}/posts
  - Description: Matches the collection’s JSON.
- If the collection doesn’t appear:
  - Check Postman’s console (View > Show Postman Console, shortcut: Ctrl+Alt+C ) for errors (e.g., “Invalid schema”).
  - Re-import the file or try the Raw Text method.
  - Ensure sufficient workspace permissions (for team workspaces).
- Edge Cases:
  - Partial Import: If only some requests load, the JSON may be truncated; re-validate the file.
  - Encoding Issues: Save the file as UTF-8 to avoid character errors ( file -i jsonplaceholder-collection.json on Linux).
  - Memory Constraints: Large collections may require closing other Postman tabs.
- Why It Matters: A successful import confirms the collection is ready for configuration, preventing downstream errors.

Configure the Collection

The JSONPlaceholder collection uses a single variable ( baseUrl ) and requires no authentication. This step ensures the collection is fully configured for testing.

1. Set Up Environment Variables

Action: Create an environment to manage the baseUrl variable.
Explanation: Environments store dynamic values (e.g., URLs, keys, tokens), allowing collections to be portable across different API instances (e.g., staging, production). While the sample collection defines baseUrl at the collection level, moving it to an environment follows best practices for flexibility and security, especially for sensitive data.
Details:
- Create an environment:
  - Click Environments in the left sidebar or the gear icon (top-right) > “Manage Environments.”
  - Click Add (blue button).
  - Name the environment “JSONPlaceholder” (or “JSONPlaceholder Prod” for clarity).
  - Add a variable:
    - Key: baseUrl
    - Value: https://jsonplaceholder.typicode.com (no trailing slash for consistency).
    - Type: Default (string).
    - Initial Value: Same as “Value” (for team sharing).
    - Current Value: Same as “Value” (for local use).
  - Click Save (bottom-right).
- Click Save (bottom-right).
- Select the environment:
  - In the top-right dropdown, change “No Environment” to “JSONPlaceholder.”
- Optional: Remove the collection-level baseUrl to rely solely on the environment:
  - Right-click “JSONPlaceholder API” > Edit.
  - Go to the Variables tab.
  - Delete the baseUrl entry (click the trash icon).
  - Click Save.
- Verify variable resolution:
  - Open “Get All Posts” and check the URL ( {{baseUrl}}/posts ).
  - Hover over ( ({{baseUrl}} to see a tooltip with https://jsonplaceholder.typicode.com )).
- Edge Cases:
  - Trailing Slash: If baseUrl includes a trailing slash (e.g., https://jsonplaceholder.typicode.com/ ), ensure request paths don’t double-slash (e.g., //posts).
  - Undefined Variables: If requests show {{baseUrl}} unresolved (red text), ensure the environment is selected and the variable is defined.
  - Multiple Environments: Create additional environments (e.g., “JSONPlaceholder Mock” with a mock URL) for testing different setups.
  - Case Sensitivity: Variable names are case-sensitive ( baseUrl ≠ BaseUrl ).
- Why It Matters: Environment variables enhance portability, security, and maintainability, allowing easy switching between environments without modifying the collection.

2. Configure Authentication

Action: Verify that no authentication is required for JSONPlaceholder.
Explanation: Many APIs require authentication (e.g., API keys, OAuth, Bearer tokens) to restrict access. JSONPlaceholder is a public API with no authentication, simplifying setup. This step ensures no auth misconfigurations cause request failures.
Details:
- Check collection-level authentication:
  - Right-click “JSONPlaceholder API” > Edit.
  - Go to the Authorization tab.
  - Confirm “No Auth” is selected (default).
  - Click Save if changes are made.
- Click Save if changes are made:
  - Open each request (e.g., “Get All Posts”).
  - Go to the Authorization tab.
  - Ensure “Inherit auth from parent” is selected (inherits “No Auth” from the collection).
- For real-world APIs, configure auth as needed (examples):
  - API Key:
    - Select “API Key” in Authorization.
    - Add key (e.g., api_key ) and value (e.g., {{apiKey}} ) to headers or query params..
    - Define apiKey in the environment.
  - Bearer Token:
    - Select “Bearer Token.”
    - Enter {{tokn}} or a static token.
    - Define apiKey in the environment.
  - OAuth 2.0:
    - Select “OAuth 2.0.”
    - Configure client ID, secret, scopes, and token endpoint (per API docs).
    - Click “Get New Access Token” to authenticate.
- Edge Cases:
  - Hidden Auth: If JSONPlaceholder unexpectedly returns 401 Unauthorized, check for - undocumented requirements (unlikely).
  - Token Expiry: For other APIs, refresh tokens if 401 errors occur.
  - Misconfigured Auth: Ensure child requests inherit correctly (avoid overriding “No Auth” unnecessarily).
- Why It Matters: Correct auth setup prevents access-related errors, ensuring requests execute successfully.

3. Review Collection Settings

Action: Inspect the collection for additional configuration needs.
Explanation: Collections may include pre-request scripts, tests, or variables that require setup. Reviewing all settings ensures the collection is fully operational and free of errors.
Details:
Right-click “JSONPlaceholder API” > Edit.
Check tabs:
- Variables: Empty if baseUrl was moved to the environment; otherwise, verify baseUrl value.
- Authorization: “No Auth” (confirmed above).
- Pre-request Scripts: Empty in this collection (used for tasks like setting dynamic headers, e.g., pm.request.headers.add({key: 'X-Timestamp', value: Date.now()}) ).
- Tests: Empty (used for response validation, e.g., pm.test("Status is 200", () => pm.response.to.have.status(200)) ).
- Description: Matches the collection’s purpose.
Review each request:
- Get All Posts:
  - Method: GET
  - URL: {{baseUrl}}/posts
  - Headers: None.
  - Body: None.
- Get Post by ID:
  - Similar to above, with URL {{baseUrl}}/posts/1
- Get Posts by User ID:
  - URL: {{baseUrl}}/posts?userId=1
  - Query params: userId=1 (visible in Params tab).
  - Body: None.
- Create Post:
  - Method: POST
  - URL: {{baseUrl}}/posts
  - Headers: Content-Type: application/json.
  - Body: JSON payload:
  Sample JSON Body
```
{
    "title": "Sample Post",
    "body": "This is a test post created via Postman",
    "userId": 1
}
```
Get all users:
- Method: GET
- URL: {{baseUrl}}/users
Edge Cases:
- Invalid JSON: Validate the “Create Post” body in a JSON linter.
- Script Errors: If scripts reference undefined variables, define them in the environment.
- Deprecated Settings: Ensure headers/methods align with API docs (e.g., JSONPlaceholder expects application/json for POST).
Why It Matters: A thorough review catches misconfigurations that could cause request failures, ensuring a smooth testing experience.

Test the API Collection

Testing involves sending requests and analyzing responses to verify the API and collection function correctly. Below, I’ll execute each request in the collection, providing detailed request/response examples as sent/received by Postman.

Send Individual Requests

Action: Execute each request and validate the response.
Explanation: Testing confirms that the API responds as expected and that the collection is correctly configured. Postman sends HTTP requests to the API server ( jsonplaceholder.typicode.com ) and displays responses, including status codes, headers, and bodies. Each request below includes a raw HTTP request (as sent) and response (as received), mimicking real API interactions.
Details:
- Ensure the “JSONPlaceholder” environment is selected (top-right dropdown).
- Test each request in the “Posts” and “Users” folders.
- Use Postman’s response panel to analyze:
  - Status: HTTP status code (e.g., 200 OK, 201 Created ).
  - Body: Response data (JSON for JSONPlaceholder).
  - Headers: Metadata (e.g., Content-Type, Content-Length ).
  - Time: Response time (typically < 500ms for JSONPlaceholder).
  - Size: Response size (e.g., ~12KB for 100 posts).

Request 1: Get All Posts (Posts Folder)

Action: Send the “Get All Posts” request.
Details:
- Open “JSONPlaceholder API” > “Posts” > “Get All Posts.”
- Verify:
  - Method: GET
  - URL: {{baseUrl}}/posts (resolves to https://jsonplaceholder.typicode.com/posts ).
  - Headers: None
  - Body: None
  - Params: None
- Example Request (raw HTTP as sent by Postman):
Example Request (raw HTTP as sent by Postman)
```
GET /posts HTTP/1.1
Host: jsonplaceholder.typicode.com
User-Agent: PostmanRuntime/7.36.0
Accept: */*
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
```
- Example Response (raw HTTP as received):
Example Response (raw HTTP as received)
```
HTTP/1.1 200 OK
Date: 
Content-Type: application/json; charset=utf-8
Content-Length: 12345
Connection: keep-alive
Access-Control-Allow-Origin: *
ETag: W/"3039-abc123"

[
{
    "userId": 1,
    "id": 1,
    "title": "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
    "body": "quia et suscipit
suscipit recusandae consequuntur expedita et cum
reprehenderit molestiae ut ut quas totam
nostrum rerum est autem sunt rem eveniet architecto"
},
{
    "userId": 1,
    "id": 2,
    "title": "qui est esse",
    "body": "est rerum tempore vitae
sequi sint nihil reprehenderit dolor beatae ea dolores neque
fugiat blanditiis voluptate porro vel nihil molestiae ut reiciendis"
},
... (98 more posts)
]
```
- Analysis:
  - Status: GET
  - Body: JSON array of 100 post objects, each with:
    - userId: Integer (1–10)
    - id: Integer (1–100)
    - title: String
    - body: String
  - Headers:
    - Content-Type: application/json; charset=utf-8: Confirms JSON format.
    - Content-Length: 12345: Approximate size (~12KB).
    - Access-Control-Allow-Origin: *: Allows cross-origin requests (public API).
  - Time: ~200–500ms (depends on network).
  - Size: ~12KB (compressed).
  - Edge Cases:
    - Empty Response: Check baseUrl or internet connection ( ping jsonplaceholder.typicode.com ).
    - 504 Gateway Timeout: Retry after a delay (server overload, rare for JSONPlaceholder).
    - Malformed JSON: Report to JSONPlaceholder maintainers (unlikely).

Request 2: Get Post by ID (Posts Folder)

Action: Send the “Get Post by ID” request.

Details:

Open “Get Post by ID.”
Verify:
- Method: GET
- URL: {{baseUrl}}/posts/1 (resolves to https://jsonplaceholder.typicode.com/posts/1 ).
- Headers: None
- Body: None
Click Send.
Example Request:

Example Request

GET /posts/1 HTTP/1.1
Host: jsonplaceholder.typicode.com
User-Agent: PostmanRuntime/7.36.0
Accept: */*
Accept-Encoding: gzip, deflate, br
Connection: keep-alive

Example Response:

Example Response

HTTP/1.1 200 OK
Date: 
Content-Type: application/json; charset=utf-8
Content-Length: 292
Connection: keep-alive
Access-Control-Allow-Origin: *

[
{
    "userId": 1,
    "id": 1,
    "title": "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
    "body": "quia et suscipit
suscipit recusandae consequuntur expedita et cum
reprehenderit molestiae ut ut quas totam
nostrum rerum est autem sunt rem eveniet architecto"
}  
]

Analysis:
- Status: 200 OK
- Body: Single post object with userId, id, title, and body.
- Headers: JSON content type, small payload size (~292 bytes).
- Time: ~100–300ms
- Size: ~300 bytes
- Edge Cases:
  - 404 Not Found: Verify the ID ( 1 s valid; IDs > 100 return 404).
  - Slow Response: Check network latency ( traceroute jsonplaceholder.typicode.com ).

Request 3: Get Posts by User ID (Posts Folder)

Action: Send the “Get Posts by User ID” request.