How to Use an API: Step-by-Step Guide With Real Examples

Introduction

I’m not ashamed to say it — I love convenience. I get groceries delivered, track my food orders in real time, check traffic before heading out, and double-check the weather just to confirm it's a stay-home kind of day. All from my phone, without leaving the couch.

What powers all this modern magic? APIs.

Application programs always have a set of API (Application Programming Interface) endpoint or single API, which allows you to access data from one application to another. In normal word this API endpoint allows two different people to communicate with each other. API endpoints are also called API keys.

Whether you’re buildings an app, connecting platforms, or just curious how everything clicks behind the scenes, this guide will help you understand what APIs are, why they matter, and how to start using them.

Why Should You Use an API?

Without APIs, we’d be stuck in the analog world, think paper maps, manual data entry, and apps that don’t communicate and talk to each other. Luckily. APIs make modern life smoother by allowing apps to tap into existing systems and data sources. So when you open a navigation app, it’s not building everything from scratch, it’s using an API to request real-time data from GPS satellites, traffic systems, and more.

For developers, APIs are time savers, this helps them to plug into services like Google Maps, Stripe, etc instead of rebuilding tools that already exist. Let them focus on creating what makes their product unique. For instance, let’s take flight-tracking apps, many of them use mapping APIs instead of designing their own visual interface, so they can concentrate on live plane data instead.

APIs also power the integrations we rely on in business. Want your CRM to update when someone books a meeting? Or your email tool to trigger follow-ups automatically?

Platforms like Klamp.io and Zapier use them to connect your entire software stack, without requiring a single line of code.

Some of the API terms you should get to know before getting started:

• API key (access code which is use to access app)
• Endpoint (Url endpoint through which an API receives and processes resource-related request)
• Request method (tells the API what to do using standard HTTP methods such as GET, POST, PUT, DELETE).
• API call (it is a process of a client making a API request to a server)
• Status code ( number in th API’s response that tells you if what you asked for worked or not)
• API server (validates and handles API request, then returns the appropriate response)
• API response (data returned by the API server to the client following a request )

Types of APIs You Might Work With

understanding the types of APIs you might work with is essential. APIs vary in their architecture, intended use, accessibility, and method of communication. Choosing the right API depends on what you want to accomplish, whether it’s connecting third-party tools, enabling data exchange, or building custom features into your product.

Let’s explore the most common types of APIs you’re likely to encounter, their strengths, and where each is typically used.

Open APIs

Open APIs are publicly available to developers and other users with minimal restrictions. They are intended to be easily accessed and used by anyone, which helps organizations expand their ecosystem.

Why they matter:

Open APIs facilitate business expansion by enabling external developers to build integrations, extensions, or complete applications that work with their platform. They’re often well-documented and play an important role in SaaS integrations and partnerships.

Partner APIs

Partner APIs are shared externally but only with specific business partners. They require authentication and are typically governed by a contractual agreement.

Why they matter:

Partner APIs facilitate secure and comprehensive integrations while offering greater control compared to open APIs.They’re ideal when sensitive data is involved or when integrations are business-critical.

Internal APIs

Internal APIs are applied only inside one company. They connect systems, services, or apps behind the scenes and are not exposed to external users or developers.

Why they matter:

These APIs improve operational efficiency and help teams build internal tools faster. As companies scale, well-designed internal APIs become vital for modularity and reuse.

Composite APIs

Composite APIs bundle multiple API calls into a single call. This is especially useful when you need to interact with multiple services or data sources simultaneously.

Why they matter:

They reduce latency, improve performance, and simplify front-end logic, making them valuable in modern web and mobile applications.

REST APIs

REST APIs are the most used APIs nowadays, as they are more flexible. The Client requests data from the server, and the server processes the client input to trigger internal functions to return the data to the client.

Why they matter:

REST APIs are simple, lightweight, and widely adopted. Their standardized approach makes them ideal for building and consuming scalable web services.

SOAP APIs

SOAP APIs used to exchange messages in XML format. It is called Simple Object Access Protocol, and it’s less flexible.

Why they matter:

Although SOAP APIs are more rigid and complex than REST, they remain essential for systems requiring strict security, compliance, and reliability.

How to Use an API: Step-by-Step

Whether you’re syncing data between a CRM and a marketing platform or automating workflows in a SaaS product. APIs are what makes it all work.

But how do you use an API?, and using a developer-friendly language like TypeScript?

This guide will lead you through methodically using an API step-by-step. Although we won’t write an entire application, we will go over the whole process using real-time examples.

Choose an API

Pick an API you want to work with, for instance, if you want to pull user information from an external service. In that case, you’ll use the /users endpoint from JSONPlaceholder.

Most of the APIs come with documentation details:

• Base URL (e.g, https://jsonplaceholder.typicode.com)
• Available endpoints (such as /users, /posts)
• Supported request methods (GET, POST, PUT, DELETE)
• Parameters (optional filters and body data)
• Authentication requirements(API key)

Create your TypeScript project starting here.

Set up a basic Node.js project with TypeScript.

axios: Promise-based HTTP client we’ll use to make API calls.

ts-node: Lets you run TypeScript files directly without compiling them manually.

Understand the API request structure

To make an API call, you’ll typically need the following:

• HTTP method (GET, POST, etc.)

• URL/endpoint

• Headers (such as authorization or content type)

• Request body (for POST/PUT)

• Query parameters (optional)

In TypeScript, we'll be using axios to make requests. Here's a simplified example:

import axios from 'axios';

async function fetchUsers() { try { const response = await axios.get('https://jsonplaceholder.typicode.com/users'); console.log(response.data); } catch (error) { console.error('Error fetching users:', error); } } fetchUsers();

This function sends a GET request to the /users endpoint and logs the response to the console. It’s simple, but this is the core of how all API interactions work.

Handle Authentication

Some APIs are public (like JSONPlaceholder), but most real-world APIs require authentication. Common methods include:

• API keys in headers or query strings

• OAuth 2.0 tokens

• JWTs (JSON Web Tokens)

Here’s an example of how you might pass a token in the header:

const headers = { Authorization: `Bearer YOUR_ACCESS_TOKEN`, }; const response = await axios.get('https://api.example.com/data', { headers });

Always store sensitive data like tokens in environment variables, not hard-coded in your codebase.

Use the response data

The response from most APIs comes in JSON format. In TypeScript, you can define an interface to represent the structure of the expected response:

interface User { id: number; name: string; email: string; } async function fetchTypedUsers() { const response = await axios.get<User[]>('https://jsonplaceholder.typicode.com/users'); response.data.forEach(user => { console.log(`${user.name} (${user.email})`); }); }

Using interfaces in TypeScript gives you better code intelligence, type checking, and auto-completion.

Make POST requests

To send data to an API (e.g., creating a new user), you’ll use a POST request and include a JSON payload in the body:

const newUser = { name: 'John Doe', email: 'john@example.com', }; const response = await axios.post('https://jsonplaceholder.typicode.com/users', newUser); console.log('Created user:', response.data);

Use PUT for updates and DELETE for deletions—just like working with a database, but over HTTP.

Manage Mistakes elegantly

Not every API call will succeed. Handle failures with try/catch blocks and inspect the error response:

Using an API with TypeScript is a valuable skill for developers building web apps, automation scripts, or SaaS integrations. Once you understand the basic steps of finding the API, reading the docs, authenticating, making requests, and handling responses you’ll be able to work with nearly any service out there.

Using an API Key the Right Way

Whether you’re integrating third-party service, for building mobile apps, or claiming SaaS products it is important to use API keys currently as it is not only essential for functionality, but also for security, scalability, and data production.

Let’s discuss in detail how to use an API key the right way.

What is an API key?

An API key is an unique identifier passed along with an API request. IT verifies the identity of the application or user initiating the request. This key is usually provided by the service provider and can be likened to a digital ID card for your application, access to most APIs is restricted without it.

But simply having an API key alone isn't enough. It must be used properly and securely to avoid potential vulnerabilities and misuse.

How to Use an API to Get Data

APIs (Application Programming Interfaces), serve as the foundation for contemporary software integrations. They enable various applications to interact and share data in a secure and efficient manner. Mastering the process of retrieving data from an API is essential if you are developing customer data pipelines, automation tools, or integrations.

Here’s a simple breakdown of how to use an API to get data:

Get Access (API Key or Token)

Most APIs require authentication. You'll usually sign up for an API key or OAuth token from the platform you're trying to connect with (like HubSpot, Salesforce, or Shopify). This key acts like a password, so keep it secure.

Understand the API Endpoint

An endpoint is a URL that defines the data you want to access. For example, an endpoint might look like this:

This could return a list of all customers in the platform.

Make a GET request

Use a tool like Postman, curl, or your programming language (like Python or JavaScript) to send a GET request to the API endpoint. A basic GET request fetches data.

Here’s an example using curl:

Response

The API will return data, usually in JSON format. You can then parse and use this data in your app, report, or integration workflow.

Using APIs to retrieve data is essential for SaaS teams focused on automation, integration, or analytics. After you become proficient with basic requests, you can begin to create more dynamic and scalable data processes.

Common Pitfalls to Avoid

Customer data integration (CDI) may provide important insights, enhance user experiences, and increase operational efficiency, but only when done correctly. Many companies go right into integration initiatives without really appreciating the complexities involved. They therefore run into delays, data discrepancies, and even compliance concerns.

Here are some of the most common pitfalls to avoid when implementing customer data integration:

• A frequent error is initiating integration without a clear data strategy. Many organizations integrate tools merely for the sake of doing so, lacking an understanding of which data is important, how it will be utilized, or its intended path.

• Combining data from various sources frequently results in inconsistencies in formats, duplicate entries, and missing information. If the data isn't properly cleaned and standardized, you're merely aggregating flawed data from different locations.

• It’s tempting to connect everything to everything. But too many custom-built integrations can create an unmanageable mess of dependencies, breaking workflows every time a platform updates its API.

• Relying on daily data pulls or manual updates can result in outdated information, negatively impacting customer experiences. This is particularly crucial in sectors such as E-commerce and support, where timely information is essential.

• Data integration is often handled by IT or engineering teams without input from marketing, sales, or support, who are the actual users of the data. This leads to misaligned priorities and integrations that don’t solve real problems.

• Combining consumer data across many technologies expands the region of data access prone to breaches. Many firms fail to install encryption, access restrictions, or audit logs, putting confidential customer information at risk.

• Even after successful implementation, integrations can fail silently over time due to expired API tokens, schema changes, or downtime. If no one’s watching, data pipelines quietly break—and decisions start relying on bad data.

Klamp.io Tip: How to Automate API Workflows

Businesses operate in a world powered by APIs. Whether it’s syncing customer data between CRMs, sending real-time alerts, or triggering personalized messages, APIs enable software platforms to communicate seamlessly. But building these workflows from scratch can be complex, especially if you're juggling multiple platforms, authentication rules, and error handling.

This is where Klamp.io plays a role, it's an embedded Integration Platform as a Service (iPaaS) aimed at simplifying automation and integration for SaaS companies, minimizing the workload for development teams.

we’ll walk through a real-world automation using Klamp:

“Whenever a new opportunity is created in Salesforce, automatically send a template without a header in Interakt.”

This example illustrates how straightforward API-driven automation can enable teams to react more quickly to leads and maintain clear communication with customers, all without the need for any coding.

Why automating API workflows matters

Imagine your sales team utilizes Salesforce for tracking leads and opportunities. You aim to ensure that whenever a new opportunity is generated, the prospect promptly receives a WhatsApp message through Interakt, a widely used WhatsApp Business Platform.

The message doesn’t need a fancy header, just a clear, pre-approved template that confirms their interest and nudges them toward the next step.

Manual handoffs between Salesforce and Interakt? Too slow.

Spaghetti-code integrations? Too risky.

Klamp.io’s automated API workflows? Just right.

Guide on how to automate this workflow in Klamp.io

Here’s how you can set up this workflow inside Klamp.io in just a few clicks:

1. Set the Trigger: New Opportunity in Salesforce

Start by choosing Salesforce as your trigger app inside Klamp.

Trigger Type: New Opportunity Created

Connection: Authenticate your Salesforce account (OAuth or token-based)

Fields to Watch: Opportunity Name, Contact Info, Stage, etc.

Klamp will continuously monitor Salesforce for new opportunities, so this step acts as your workflow’s entry point.

2. Add a Filter (Optional but Powerful)

Let’s say you only want to send messages for high-value deals or when a specific field is filled out (like contact phone number). You can use Klamp’s filtering logic:

Condition: Opportunity Value > $X or WhatsApp Number is not empty

Action: Proceed only if the conditions are met

This prevents unnecessary pings and keeps messaging targeted.

3. Set the Action: Send WhatsApp Template via Interakt

Now, choose Interakt as your destination app.

Action Type: Send Template Message

Template Name: “opportunity_follow_up”

Header: None

Message Body: Customizable placeholders (e.g., {{name}}, {{deal_stage}})

Phone Number: Pulled directly from the Salesforce opportunity record

Klamp’s Interakt connector comes with built-in support for template formatting, including the ability to skip the header section entirely just like in our use case.

4. Test and Deploy

Klamp lets you test the entire workflow in a sandbox environment before going live. Once you're confident everything is working, deploy the automation.

Now, every time your sales team creates a new opportunity, your prospect automatically receives a personalized message on WhatsApp without any manual intervention.

Conclusion

Automating API workflows has become a necessity for contemporary SaaS companies aiming to enhance speed and customer service, rather than a mere advantage for large enterprises. Klamp.io offers a dependable and scalable solution that eliminates the need for creating custom scripts or starting from scratch. It allows you to seamlessly integrate your applications and automate important tasks, such as dispatching a WhatsApp template upon the creation of a Salesforce opportunity.

It’s automation made simple. It’s integration without friction.

It’s how modern SaaS teams work smarter.

👉 Want to try building your first automated API workflow? Get started with Klamp.io today.

FAQ

What are the first steps to start using an API in my project?

Start by reading the API docs, get an API key, test endpoints with tools like Postman, then integrate with your code using HTTP requests.

Can I use an API without being a developer?

Absolutely!

You can use an API without needing programming skills by employing no-code platforms such as Zapier, Klamp, or Make. These tools enable you to link applications and automate processes through APIs without any coding. Simply drag, drop, and set up your configurations.

What tools or platforms can help me test an API quickly?

Here are some popular tools and platforms that can help you quickly test an API:

Postman – The most widely used API testing tool. Great for sending requests, viewing responses, and organizing test collections.

Insomnia – A lightweight, developer-friendly REST and GraphQL client for testing APIs with an intuitive interface.

cURL – A command-line tool ideal for quick API testing directly from your terminal or script.

Swagger UI / SwaggerHub – Great for testing APIs documented with OpenAPI. Lets you interact with endpoints directly from the browser.

Hoppscotch – A fast, open-source alternative to Postman for testing REST, GraphQL, and WebSocket APIs.

RapidAPI – A marketplace and testing platform where you can find and test thousands of APIs in one place.

Each of these lets you send API requests, inspect responses, and debug integrations without writing full code.

How do I securely store and manage API keys?

To securely store and manage API keys, follow these best practices:

Use Environment Variables

Store API keys in environment variables instead of hardcoding them into your application. This keeps your keys out of your codebase.

Keep Keys Out of Version Control

Use .gitignore to exclude files containing sensitive keys from Git repositories. Never commit API keys to GitHub or any VCS.

Use Secret Managers

Tools like AWS Secrets Manager, HashiCorp Vault, Google Secret Manager, or Azure Key Vault offer secure, encrypted storage for API keys.

Restrict Key Permissions

Only grant the minimum permissions necessary for each key. Apply the principle of least privilege.

Rotate Keys Regularly

Change your API keys periodically to reduce the impact of a potential leak or misuse.

Monitor Usage

Enable usage monitoring or alerts to detect any unusual activity with your keys.

Use HTTPS

Always transmit API keys over HTTPS to protect them from being intercepted.

Avoid Client-Side Exposure

Never expose sensitive API keys in frontend code (e.g., JavaScript running in browsers).

By following these steps, you can significantly reduce the risk of your API keys being leaked or misused.

How do I read and process the data returned by an API?

To read and process API data:

• Send a request using tools like Postman or code (e.g., fetch in JS).

• Get the response, usually in JSON format.

• Parse the data to access specific values.

• Use it in your app display, store, or trigger actions.

Always refer to the API docs for structure and usage!