How To Turn a Spreadsheet Into an API in Minutes

As a developer, you’ve likely used APIs, short for Application Programming Interfaces, to access things like real-time weather data, housing prices, or product listings. But building one from scratch usually requires backend knowledge, infrastructure setup, and database configuration.

That’s where MantaHQ comes in. We take all that complexity away. It’s a powerful tool for frontend developers who want to skip backend setup, backend developers who need to move fast without a boilerplate, or anyone trying to turn data into something useful, fast.

By the end of this guide, you’ll have built and tested a live API from a spreadsheet, ready to use in your next project.

Prerequisites

To follow along with this guide, you’ll need:

• A modern browser and a text editor

• Basic knowledge of any programming language (we’ll use JavaScript in this guide)

• A MantaHQ account

What is MantaHQ?

MantaHQ, or simply Manta, is a low-code platform that lets you turn raw data, like spreadsheets, into fully functional APIs in minutes. Without needing backend knowledge, you can create, manage, and launch APIs effortlessly.

Why use MantaHQ?

MantaHQ helps you turn ideas into APIs quickly, without setting up a backend or writing infrastructure code. Here's how Manta does that:

• Backend setup: No need to write server logic or route handlers.

• Server configuration: Avoid hosting and deployment stress.

• Database management: Your spreadsheet is the database.

• Authentication: Built-in access control for your APIs.

• Error handling and documentation: Manta provides API previews, error responses, and auto-generated docs.

Manta is ideal for:

• MVP development: Test your idea fast.

• Learning projects: Focus on API concepts, not backend complexity.

• Hackathons: Build working projects within hours.

• Student projects: Great for quick demos or proof-of-concepts.

Creating an API from a Spreadsheet

Creating an API with MantaHQ is straightforward. First, you’ll need an account. If you don’t have one, sign up here by clicking Get Started. After onboarding, you should land on a dashboard like this:

Prepare the Spreadsheet

Before creating your API, you’ll need a data source, in this case, a spreadsheet.

1. Create a spreadsheet
   Use Google Sheets or Excel to create a new sheet.

2. Add header rows
   Add column headers such as name, age, gender, etc. These headers become your API field names.

3. Add data
   Populate your sheet with sample data, then export it as a .csv file.

Set Up MantaHQ

With your CSV file ready, let’s walk through how to structure it inside MantaHQ.

1. Create a workspace
   Workspaces help organize your APIs. Click Create Workspace, give it a descriptive name, and proceed. Once created, your dashboard will update.

2. Import the spreadsheet as a table
   In the left sidebar, click Data Tables, then click Create Table. Choose to upload from a CSV file.

   • Add a name and description for your table.

   • Upload the CSV you just exported.

   • Click Create Table.

Tip for header naming conventions

• Use all lowercase letters

• Replace spaces with underscores (e.g., first_name)

• Avoid special characters (#, /, @, etc.)

• Use descriptive, unique names like signup_date or customer_id

That’s it! Your spreadsheet is now part of your Manta workspace.

Generate the API Endpoint

Now, let MantaHQ generate your API endpoint.

1. Create a data service
   A data service in Manta is an API endpoint for different HTTP methods (GET, POST, PUT, DELETE). Here, we’ll create a GET service to fetch employee data.

   • Navigate to Workspaces and select your workspace.

   • Click Create New Service, then give it a name and description.

   • Select Get Data (to use the GET method), then click Next.

   • Choose My Tables on Manta, then select your uploaded table.

   • Select the fields you want to expose in the API and click Next.

   • Optionally add filters (e.g., filter by age or department), or click Skip.

   • Customize the API's response messages.

   • Click View Preview, then Create Data Service to finalize.

And just like that, you’ve turned a spreadsheet into a working API (in minutes) without writing a single line of backend code.

Testing the API

Now that your API is live, let’s test it in two ways:

• Directly inside MantaHQ

• Using your browser and JavaScript

Test the API in MantaHQ

MantaHQ automatically generates documentation for every API you create. This includes:

• The API endpoint (a URL you can send requests to)

• A description of what the API does

• A built-in testing section

To test your API:

1. From your Workspace, click on the service you just created.

2. On the service page, click Try it out.

3. Click Execute.

You should see:

• A 200 OK status code (which means the request was successful).

• A JSON response that includes your spreadsheet data.

This confirms that your API is working as expected.

Test the API in the Browser (JavaScript)

You can also test the API by making a GET request using JavaScript and viewing the results in the browser console.

Using the API in a JavaScript Project

You can also test your MantaHQ API by using it in a simple JavaScript project. Let’s build a small web app that fetches employee data from your Manta-powered API and displays it on a webpage.

1. Create the HTML File

Start by creating a file named index.html. Add the following boilerplate:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>MantaHQ API Demo</title>
  </head>
  <body>
    <h2>Employee List</h2>
    <ul class="employees"></ul>

    <script src="index.js"></script>
  </body>
</html>

The <ul class="employees"></ul> is where we’ll display the API data.

2. Create the JavaScript File

Now, create a file named index.js in the same folder. In this file, we'll use the fetch() function to call the API and display the results:

const getEmployees = async () => {
  try {
    const response = await fetch('https://api.mantahq.com/api/workflow/manta-demo/demo/get-employees');
    const result = await response.json();

    if (!response.ok) {
      throw new Error(result.message || `HTTP error! Status: ${response.status}`);
    }

    const { data } = result;
    const employeeList = document.querySelector(".employees");
    const ul = document.createElement("ul");

    data.forEach((employee) => {
      ul.innerHTML += `
        <li>
          (${employee.user_id}) ${employee.name} (${employee.age}) — ${employee.gender} is our ${employee.title} 
          in the ${employee.department} department, ${employee.unit} unit. 
          Based in ${employee.city}, ${employee.country}. 
          Earns ${employee.annual_salary} annually.
        </li>
        <br />
      `;
    });

    employeeList.appendChild(ul);
  } catch (error) {
    console.error("Error fetching employees:", error);
  }
};

getEmployees();

Explanation of the Code

• fetch() sends a GET request to your MantaHQ API endpoint.

• await response.json() extracts the JSON body from the response.

• We check if the response is successful and throw an error otherwise.

• The employee data is looped through and added to the page as list items.

• The output is rendered directly into the <ul class="employees"> element in your HTML.

Result

If everything works, your browser console should display a list fetched from your spreadsheet-powered API.

Conclusion

Congratulations! You’ve just built and tested a real API using nothing but a spreadsheet and MantaHQ. With just a few steps, your spreadsheet data is now available through a clean, structured API, ready to be used in your web apps, dashboards, or side projects. But this is just the beginning.

If you were wondering what else you can build with Manta, you're in luck because the possibilities are endless really. Here are a few practical projects that you can build next with Manta:

• User Feedback Collector
  Create a feedback form that stores responses directly into a Manta table. Then retrieve and display them using a GET endpoint. This is perfect for quick user research or product testing.

• Inventory Tracker
  Manage product stock or catalog items in a spreadsheet. With Manta, you can expose this as an API to fetch, add, or update items. This is great for small businesses or ecommerce prototypes.

• Portfolio or Resume Site
  Build a personal site where your projects, work history, or blog posts are pulled from a spreadsheet.

• Newsletter Signup System
  Connect a form to a Manta POST API that saves emails into a table.

• Event Registration Tool
  Capture RSVPs or attendee details from a form and store them in a Manta table. Later, view or export them for printing badges or check-in lists.

MantaHQ gives you just enough backend power to ship useful tools without the stress of managing infrastructure. Whether you’re:

• prototyping an MVP,

• learning how APIs work, or

• building something fast for your team

Manta helps you focus on the real value: turning your data into useful software. In the next tutorials, we'll explore how to accept POST data from your forms.