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John Au-Yeung
John Au-Yeung

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Useful Practice Apps We Can Build With Free APIs

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In the software development world, practice makes perfect. Therefore, we should find as many ways to practice programming as possible.

With free public APIs, we can practice programming by creating apps that use those APIs. After writing the practice apps, we can even pay for some APIs and write even more useful apps.

In this article, we’ll look at some practice project ideas that can use some of those APIs.

Phone Number Validator

We can use the numverify API to verify phone numbers to make sure that they’re valid.

Now we won’t have to worry about calling phone numbers that might not be used by anyone.

It works with phone numbers from 232 countries and can give us the phone company and location that the phone number is located in.

Git App

The big Git hosts all provide their own APIs to let us automate tasks that are needed to be done with them like pulling and pushing code, merging code, etc.

There’s Bitbucket, GitHub, and Gitlab, which all let us do many Git operations with them.

They’re all very secure as authentication is done using OAuth and authorization is the same as using the UI to manipulate the Git repositories.

Website / RSS Aggregator

With the API, we can aggregate data from various websites and RSS feeds and get them all from one source.

It supports CORS so we can access data right from our front end apps. An API key is required to use this API.

The data that’s aggregated with is returned in JSON so that we can use the data right away.

We can use it to crawl websites and RSS feeds and extract data as we wish. Jobs can be run on the fly and also run on a scheduled basis by setting a schedule with the API.

An App to Find Technologies Use On Other Websites

Ever curious about what technologies on websites that we visit? We can use the Let’s Validate API to create an app that reveals the technologies that are used on websites of our choice.

It doesn’t require any authentication so that we can use them right away.

API Testing App

We can use the Postman API to make our own requests to APIs with ease. It lets us write programs to script the testing of APIs by using the Postman API.

The Postman API can be used to send query strings, headers, and get response bodies and headers.

Dictionary App

With various APIs, we can create our own dictionary app with various dictionary APIs.

There’s the Merriam-Webster API, Oxford dictionary API, Wordnik API, and the Words API.

They’re all available for free as long we limit our queries and sign up for an API key to use them.

They provide definitions of words, pronunciations, word types, and more data.

In the case of the Words API, it also provides synonyms for words. The Oxford dictionary API also has a thesaurus, translations for words, sentences API to get us example sentences for a given word, and more.

If we pay, then we get access to more things like more API requests a day

File Conversion App

The Cloudmersive Document and Data Conversion app lets us write the programs to use the API to convert data between various formats.

They include converting between common formats like HTML, Office files, or photo files to PDF.

We can also use it to merge multiple Office documents into one.

Other data formats that the API can convert include CSV to JSON and XML to JSON.

Cloudmersive also makes other APIs like email validation APIs, natural language processing APIs, OCR APIs, barcode scanning APIs and more.

It can take images and then parse them into readable text with the OCR API. The barcode scanner API takes images of the barcode and returns the data from the barcode.


There’re lots of APIs that we can use to do various things like converting files, barcode scanning, OCR, and more.

We can also use APIs to automate Git operations like pushing, fetching, and pulling code from to and from repos.

Finally, we can validate data like phone numbers with various APIs.

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