Top Free APIs for All Skill Levels

August 13th, 2021 11 min read

America may run on Dunkin’, but the online world runs on APIs. In recent years, APIs have become the de-facto standard for organizations to make their data accessible. APIs are particularly important for accessing data at scale. Many of these APIs require paid access. There are also a multitude of free APIs for publicly available data.

For some, the volume of free APIs can be overwhelming. Fortunately, most APIs specialize to deliver a specific kind of data. Some exist only to provide testing data. Others target specific industries or use cases.

Not all APIs are created equal, either. Differentiating between APIs is crucial to getting the best data for your use case. Users should first understand what kind of API they need to use.

Types of APIs

APIs (Application Programming Interfaces) are standardized portals for systems to intake and output data from a database. They are often used to automatically transfer data between systems. They can also be queries manually if users know how to call the API.

There are four main types of APIs: Open APIs, Partner APIs, Internal APIs, and Composite APIs. The most relevant type for today is Open APIs. Open APIs are publicly accessible. They are usually used to make free information easier to use at scale. They can also deliver more complex data that wouldn’t conform to a CSV file.

The other relevant type of API is partner APIs. These APIs need special licensing or permissions to access. Users usually must pay for these licenses or permissions. These APIs use paywalls or restrictions because the data is restricted. The data may be proprietary, personal, or for commercial use only. Paid APIs are more likely to come with vendor support or implementation help.

There are also internal and composite APIs. Internal APIs are only used within an organization. They tend to be much more bespoke to specific tasks or functions. Composite APIs combine multiple APIs and data sources into a single function. Composite APIs can be public or private. To end users, composite APIs are no different from any other API. The specialization comes from the backend developer work necessary.

Open APIs are the only free APIs for the public, so they are our primary focus. However, it’s not always clear just how “free” and API may be.

Free vs. Freemium APIs

Freemium APIs can feel like a frustrating bait-and-switch for some users. These APIs offer some data for free, but come with restrictions. Common restrictions include:

The amount of data that users can pull
What kinds of data users can access
How granular API filters are
How often users can call the API

Freemium APIs may also require users to put down a credit card. Anyone who forgot to cancel a streaming subscription before the trial ended understands why this is concerning to some. For some, starting with a free trial and then upgrading may be worthwhile. This is especially true if real-time data is important. Freemium APIs may also require users to put down a credit card. Anyone who forgot to cancel a streaming subscription before the trial ended understands why this is concerning to some.

In fairness, free APIs may also have some of these limitations. Many free APIs will limit the call frequency. This prevents the API from getting overwhelmed by requests. However, truly free APIs will not come with restrictions on what data is free to call. Most organizations provide free APIs as a public service or for promotions. This makes it in their best interest for the API to be as easy to use as possible.

What Makes a Great API?

There are several factors that users should evaluate across all APIs. The most obvious factor is the user’s use case. A free weather API will be less than helpful if you’re looking for financial data.

More specifically, a given stock market API may not have the data in certain time increments. The way an API structures the data can be as impactful as the kind of data itself. The cleanliness, completeness, and accuracy of the data are also important factors.

There are also technical considerations. For technical users, the APIs documentation can have a dramatic impact on usability. Whether the API requires an access key can also be relevant. Key management can increase the maintenance lift over time if the API will be used often and for a long period of time.

Given these factors, the range of free API options will vary. For some use cases, there may be only one viable option. In these cases, Googling the use case may be the quickest route to the necessary API. For more popular use cases, there are a plethora of options that users can “shop” around for.

Top APIs for Popular Use Cases

Some of the most common use cases include testing data, marketing and content developers, and various specialized data-intensive users. For these users, we’ll provide some guidance on finding the best API for you. We’ll list some specific starting points to finding the best free API for your use case. There are also free API repositories. These online libraries can direct users to hundreds of potential APIs. If you don’t find what you’re looking for on this list, check out the libraries we have listed below!

Free APIs for Testing

Testing new applications, programs, or systems can be exhausting. One way to make it easier is having good testing data. Fortunately, testing APIs provide dummy data to pass through programs during testing.

Testing APIs are great for mimicking how a system would interact with data from APIs in a production environment. They also include relevant metadata. They may be more limited in testing very specialized or unusual API calls. However, they are great for testing common calls in JSON format or XML structures.

A popular format for calling data from APIs is JSON. This makes the {JSON} Placeholder API great for testing various JSON-based API calls. It offers a range of resource structures, including social media posts, photos, todo lists, and users. This flexibility allows users to use test data that resembles their production environment. This way, they can test that the system can format the JSON into the appropriate format.

Go Rest is another good option, specifically for testing RESTful API calls. Go Rest is an online REST API for testing and prototyping. REST APIs have become very common online, compared to HTTP APIs. They also have some special requirements, such as authentication tokens. This makes testing with a RESTful API crucial for some development cases.

Free APIs without Authentication Keys

There are also APIs tailored to less technical audiences. As mentioned above, many APIs require some level of authentication. Even free APIs may need authentication keys, which serve as a password. The extra steps to manage API keys can be a barrier to some users, especially beginners.

In many cases, free APIs will still have authorization keys for good reason. Access keys help protect providers from malicious users. Without keys, it would be easier for users to spam the API, potentially knocking it out of service. APIs without keys will usually have other checks, such as query limits.

For some users, it is still worthwhile to avoid the hassle of authentication keys. In these cases, there is usually some API that can deliver authentication-less data. However, it will often be more limited. Leading examples include the Archive.org APIs. They are open source APIs for web data. They also come with some scalability limitations. For instance, the Advanced Search API caps out at 10,000 sortable pages. Mixed Analytics has a more comprehensive list of free APIs with no authentication requirements.

Free API Repositories

There are far too many APIs to all break down one by one. Instead, the lists above should give you some idea of what kind of API you are looking for. More comprehensive libraries of public APIs are available below. Now that you have some starting information, these repositories should be less overwhelming:

How to Use Free APIs

So you’ve picked the API you want to use– now what? Free APIs should be pretty simple for the most part. If an API is free, it will be immediately available on the provider’s site. In some cases, you may need to download an authentication key to access the API properly.

APIs should also come with documentation. The documentation will provide the requirements to access the API, how to structure the API call, and it will deliver the data back. In most cases, this information will all be accessible under a “developer” subdomain. Sometimes, there will also be help forums for troubleshooting issues.

For personal use, the story may end here. In business contexts, developers rarely use just one API. API management tools help developers access, manage, and orchestrate their APIs. They can also automatically cover for the limitations of free APIs. For instance, they can regulate how often an API is called, so you don’t go over your limit.

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