How to Call an API?

Calling an API means actually making a request and handling the response — not just reading about it. In this article we’ll use a real-life API example for London’s weather using WeatherAPI.com and show how you can try it out using Apidog. We’ll keep it beginner-friendly.

1. What You Need Before Calling an API

Before you call an API, you typically need:

An endpoint URL (where you send the request)

The correct HTTP method (GET, POST, etc.)

Any parameters required (query strings, path segments)

Possibly headers (authentication, content type)

Sometimes a body (for POST/PUT)

You can send API requests in two main ways: by writing code (using libraries like Python's requests or JavaScript's fetch) or by using API tools like Apidog.

For this guide, we will use Apidog for convenience, as it allows you to send requests and visualize responses easily without setting up a complex development environment.

For our example we’ll use WeatherAPI.com’s current-weather API, which requires you to register, obtain an API key and then send the key as a query parameter.

2. Request (How to Send It)

What is WeatherAPI.com?

WeatherAPI.com is a fully managed weather and geolocation API provider offering real-time weather, forecasts, historical weather, air quality data and more.

You need to firstly register in WeatherAPI to get an API key to continue.

Example Request

Here’s a ready-to-send request (replace YOUR_API_KEY with the actual key you get after signing up):

GET http://api.weatherapi.com/v1/current.json?key=3432a351afd04b30bef75833252711&q=London&aqi=no

Method: GET — retrieving data

URL: Base URL http://api.weatherapi.com/v1/current.json, parameter key = your API key, q = “London”, aqi=no to skip air-quality data

No extra headers or request body needed in this simple case

What is Apidog?

Apidog is an all-in-one API collaboration platform used for API documentation, API debugging, API mocking, and API automated testing. It offers a visual interface to send HTTP requests and inspect responses easily, making it a powerful alternative to command-line tools or basic HTTP clients.

Apidog Practical Steps

Here’s how to send this request using Apidog:

Log into Apidog and select New Endpoint.

Set the Method to GET.

Paste this URL into the request URL field. Don't forget to replace the key to your own key.
http://api.weatherapi.com/v1/current.json?key=3432a351afd04b30bef75833252711&q=London&aqi=no

(Optional) Add a descriptive name like “Get realtime weather”.

Click the Send button. Apidog will fire the request and show you a live response.

By doing this you’ve initiated a real API call for London’s weather data.

3. Response (What You Get Back)

Apidog Practical Steps

After sending the request, you'll see the response under the request zone.

Here’s how to inspect the response in Apidog:

After you’ve sent the request (previous section), look at the response panel in Apidog. You should see status code 200, plus response time and the JSON body.

Expand the JSON body to review fields like daily_units, daily.time, daily.temperature_2m_max, etc.

Save the request in Apidog so you can reuse it.

(Optional) Change the query parameter q to a different city (e.g., q=New York) and resend the request to see how the response changes.

Example Response

HTTP/1.1 200 OK  
Headers: (ignored for simplicity)

{
    "location": {
        "name": "London",
        "region": "City of London, Greater London",
        "country": "United Kingdom",
        "lat": 51.5171,
        "lon": -0.1062,
        "tz_id": "Europe/London",
        "localtime_epoch": 1764232379,
        "localtime": "2025-11-27 08:32"
    },
    "current": {
        "last_updated_epoch": 1764232200,
        "last_updated": "2025-11-27 08:30",
        "temp_c": 11.2,
        "temp_f": 52.2,
        "is_day": 1,
        "condition": {
            "text": "Overcast",
            "icon": "//cdn.weatherapi.com/weather/64x64/day/122.png",
            "code": 1009
        },
        "wind_mph": 10.1,
        "wind_kph": 16.2,
        "wind_degree": 225,
        "wind_dir": "SW",
        "pressure_mb": 1015.0,
        "pressure_in": 29.97,
        "precip_mm": 0.0,
        "precip_in": 0.0,
        "humidity": 94,
        "cloud": 100,
        "feelslike_c": 9.3,
        "feelslike_f": 48.7,
        "windchill_c": 8.0,
        "windchill_f": 46.3,
        "heatindex_c": 10.2,
        "heatindex_f": 50.3,
        "dewpoint_c": 9.0,
        "dewpoint_f": 48.2,
        "vis_km": 10.0,
        "vis_miles": 6.0,
        "uv": 0.0,
        "gust_mph": 17.1,
        "gust_kph": 27.5,
        "short_rad": 0.68,
        "diff_rad": 0.31,
        "dni": 11.17,
        "gti": 0.0
    }
}

Status code 200 OK: means the request was successful.

The body contains the current weather for London, including temperature (11.2 °C), condition (“Overcast”), wind speed, humidity etc.

Your front-end or client can now use these values to display to the user.

By inspecting the response in Apidog, you’re closing the loop: request → response → usage.

You can also visit this request directly here: Get realtime weather.

4. Key Takeaways

Calling an API = making a request + handling a response.

You now know how to use a real URL, a method, send your API key, and see a real response for London’s current weather via WeatherAPI.com.

Using a tool like Apidog turns theory into practice.

Next step: try calling APIs with different cities or parameters (e.g., forecast endpoint), or use POST/PUT methods with request body for other APIs.

Calling an API is all about sending the right request and knowing how to read the response that comes back. But how do we know what should we send in the parameters or bodies? How should we compose the request?

In the next article, we’ll break down How to Read an API Documentation so you can understand any API with confidence and call it correctly.

1. What You Need Before Calling an API#

2. Request (How to Send It)#

What is WeatherAPI.com?#

Example Request#

What is Apidog?#

Apidog Practical Steps#

3. Response (What You Get Back)#

Apidog Practical Steps#

Example Response#

4. Key Takeaways#

1. What You Need Before Calling an API

2. Request (How to Send It)

What is WeatherAPI.com?

Example Request

What is Apidog?

Apidog Practical Steps

3. Response (What You Get Back)

Apidog Practical Steps

Example Response

4. Key Takeaways