Coding 13: Storing Data in the Cloud & APIs

Storing Data in the Cloud and APIs

Coding 13

Storing data in the cloud and or using an API is one way to earn maximum points in the "Code Complexity" line of the Technical section in the judging rubric. It can also help with "App Function", "User Experience and Design", and "Technical Learning". 

In this lesson, you will…

  • Learn about cloud storage and APIs
  • Create a login page

Key Terms

  • Cloud Storage - information that is stored on the web so that any device connected to the internet can access it
  • Web Database - a way to store and organize information in the cloud
  • API (Application Programming Interface)- the way you can get information from another website or database.

Web Databases and APIs

In the last coding lesson, you learned how to store information on a device, or how to use local storage. You also built a to-do list app that allowed users to save their to-do lists in between when they opened and closed the app. In this lesson, you’ll learn about cloud storage, or how to store information on the web so that any device connected to the internet can access it. Web Database is another term often used to describe cloud storage.

Cloud Storage

Let’s say you have two phones running an app, Phone A and Phone B. If Phone A stores data in local storage or a local database, Phone B can’t access it. If Phone A stores data in cloud storage or a web database, then Phone B can access the data.

Local Storage

Cloud Storage

Uses for Cloud Storage

Cloud Storage is necessary for apps to use with information that frequently changes. Here’s an example. Let’s say you are building an app to show the 10 most popular restaurants in your city each month. You put a list of restaurants into your app and upload your app to the app store. The following month, you update the list of restaurants and update your app in the app store. Users who are already using your app will need to update or re-download your app to see the new top restaurants. 

Now let’s say you stored the top 10 restaurants in cloud storage. When you update the restaurants, all of the phones using your app will check for updates to this cloud storage automatically. Users will see the changes right away, and won’t need to re-download anything.

Have you ever shared a picture on Facebook or Instagram? Apps like these use cloud storage. When your friend uploads and shares a picture, your phone checks the web database for new photos, and then you see it in your feed. 

So when would you use cloud storage? Here are some common uses:

  • Requiring login and passwords for users
  • Sharing data from a game, like a high score list
  • Allowing users to share images with each other through a feed
  • Displaying a feed that updates all users see
  • Remembering things about a user such as their transactions, financial records or medical records

It is important to know that when using cloud storage, phones need to have an internet connection to get information. If the phone has a slow internet connection, this could slow down your app or make it impossible for your app to update.

There are a few different options for cloud storage in App Inventor. Most of these are called web databases. The activity in this lesson uses CloudDB in App Inventor and Realtime DB in Thunkable.


API stands for application programming interface. An API is a way you can get information from another website or another website’s database.

Let’s say you are building an app to help people decide what to wear based on the weather. You could spend lots of time uploading data about the weather into a database, but there are already websites that show the weather.  A better solution would be just to grab data from that website and show it to your users through your app. An API is what would allow you to do this.

Here are some common APIs that programmers use when they create apps:


You can learn more about APIs in Thunkable by watching this video and checking out resources here.

Google Maps

Location and Map Information

App Inventor Tutorial

Thunkable Tutorial


Activity: Create a Login Screen Using Cloud Storage

This app allows users to create an account and log in. It uses CloudDB in App Inventor and Cloud Variables in Thunkable. Here’s how it works:

When a new user signs up, it saves their username and password in the cloud

When a user logs in, it calls the cloud database to get their username and password

If the user successfully logs in, the app takes them to their profile page

However, this app has a major security bug! It never checks to see if the user’s password matches the one in the cloud storage before logging in. This means that any user can log in to any account. You need to fix this bug and alert the user if they have an incorrect username or password.

You need to make sure that the value returned from the cloud storage matches the password the user entered into the textbox! Ready to get started? Download the source code below.

By default, the cloud variable is saved to the Thunkable default Firebase database but you can save them to your own private Firebase database by following the instructions here.


There are so many ways you can use web databases! What other ways can you and your team think of to use them in your app? Can you think of some other real world examples that might be using them?