How to Fetch ISS Data with Python: A Beginner’s Guide to APIs

An API (Application Programming Interface) is a server-provided code endpoint that allows you to send or receive data, typically used for data retrieval.

To make API requests in Python, install the requests library using pip install requests or, if you use conda, conda install requests. Then import it with import requests.

Create a GET request with

response = requests.get("http://api.open-notify.org/this-api-response-exist/")

and check the status code via print(response.status_code). A 404 status indicates the requested resource does not exist.

Common HTTP status codes include:

200 – Success

301 – Redirect

400 – Bad request

401 – Unauthorized

403 – Forbidden

404 – Not found

503 – Service unavailable

Always refer to the API documentation before making requests.

We will use the Open Notify API ( http://open-notify.org/ ) to retrieve data about the International Space Station. The endpoint http://api.open-notify.org/astros.json returns JSON data about astronauts currently in space.

Make the request:

response = requests.get("http://api.open-notify.org/astros.json")
print(response.status_code)
print(response.json())

The response status 200 confirms success, and the JSON payload can be accessed with response.json().

JSON is the standard data format for APIs. In Python, the built‑in json module handles JSON serialization and deserialization. Use json.dumps() to convert a Python object to a JSON‑formatted string, and json.loads() to parse a JSON string back into a Python object.

Example helper to pretty‑print JSON:

import json

def jprint(obj):
    text = json.dumps(obj, sort_keys=True, indent=4)
    print(text)

jprint(response.json())

This prints the formatted JSON showing six astronauts aboard the ISS, each represented as a dictionary within a list.