API is short for Application Programming Interface. An API is an intermediary that relays communication between two programs in a format each respective application can interpret. This allows owners to expose a part of the product’s functionality to third parties while keeping the rest of the application safe.

As a marketer or content developer, this is a great chance to access the systems of major products and try to create new functionality.

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However, because the proprietary organization needs to maintain a level of safety and management with the tool, there are certain limits to open APIs. API management ensures the application remains the best it can be to ensure all users enjoy the same benefits.

Publishing an open API might seem counterintuitive because of the security challenges. However, it can also be an effective way of encouraging innovation and making your product better suited for the market.

We’ve rounded up a list of the best free APIs you can use for your marketing or content development projects.

1. HubSpot API

With the HubSpot API, you can build a custom solution specifically for your business. You’re able to add advanced functionality to an already powerful marketing software and sync your HubSpot account with other tools. 

2. Hunter API

Hunter API for email allows you to find or verify the email addresses of professionals and companies. It can come in handy if you want to reach people whose contact information isn’t readily available publicly.

3. Sejda PDF API

The Sejda PDF API for website integration allows you to integrate its PDF tools with your website and fill out PDF forms online. It also lets you streamline communication with others (such as vendors) by automatically sharing signed documents or PDF forms they need to fill out. Your customers can also copy your PDF templates easily.

4. Placekitten API

Who says work always has to be serious? Placekitten randomly generates amusing pictures of cute cats and kittens. You can use it to improve the mood around your website or simply put a smile on a colleague’s face.

free open api placekitten


5. APIMeme

Another fun API is the APIMeme. It lets you generate memes using a simple interface. With over 100 popular meme characters (like Condescending Wonka, Confession Bear, Confused Gandalf, Eminem, and Family Guy Brian), all that’s missing is a dose of your wit.

6. QRcode Monkey

The QRcode Monkey API allows you to create all kinds of custom QR codes to add to your website or workflow. It’s accessible through RapidAPI.

7. QuickChart

Use QuickChart to quickly generate chart and graph images that you can embed in email, chatbots, and SMS. It uses Chart.js, a robust open-source charting library. You can create a simple chart with a single URL. For more sophisticated charts, use the POST request.

free open api quickchart


8. IPLegit

IPLegit is a service that allows you to identify bad users on your application using their IP address. The tool tracks millions of IP addresses to give you data on their fraud scores. You can then use this information to block known bad actors before they ever get to your product. This is one of the most important APIs you can use for cybersecurity.

While it’s not entirely free, IPLegit offers 5,000 free requests per day — enough to get started.

9. Shutterstock API

The Shutterstock API provides access to Shutterstock’s library, allowing you to search, view information, preview, license, and download media. This includes royalty-free images, music tracks, and video clips. Use it to improve your site’s aesthetics and express your brand better with high-quality media.

10. Square API

Although all three are payment gateways, Square is unlike Stripe and PayPal. Rather than just letting customers send you payments, it lets you customize the payment gateway itself. You can create gateways for your mobile app, website, and even your physical point-of-sale system. This improves the checkout process and user experience in general.

Note: The API is free, but Square charges a processing fee for all transactions.

free open api square


11. Yahoo Search Marketing API

The Yahoo Search Marketing API lets you access Yahoo marketing data you can use to manage your marketing campaigns.

12. Telegram APIs

Telegram is a messaging service with two APIs. The first is the Bot API, which lets you connect bots to Telegram — allowing you to use the messages as an interface. The second is the Telegram API that lets you build your own version of Telegram with full customization of the design.

13. Common Crawl

Crawling tools are effective because they can access internet data anonymously. This makes large amounts of data available for analysis and interpretation for any team. Few can do it like Common Crawl, which builds and maintains a repository of data, then makes it accessible by anyone.

free open api common crawl



IFTTT makes it possible to make your applications and devices work together by using simple “if this, then that” criteria. This means that one action is triggered by another as defined by you.

For instance, you can set a photo or blog post to be shared across all platforms whenever it’s posted on one platform. If you want to go bigger, you can build a smart house system that guides the pizza guy all the way to your bedroom so you never have to get up to open the door.

15. WordPress APIs

The WordPress APIs are an ecosystem of APIs that can be used to extend WordPress capabilities. They are sorted into categories to help you to find what you need.

16. Yelp API

With the Yelp API, you can access review data sorted geographically and filter by ratings and distance from location. You can use this to improve your local marketing efforts.

free open api yelp


17. Google APIs

There are various Google APIs that make it easier to work with Google’s many products: from Blogger to AMP and AdSense.

18. Local API

This is another local marketing API that can help you better understand your local audience by giving you access to user-generated content and location-based information.

19. Awe.sm

Awe.sm offers a number of APIs to integrate your social media marketing tools with your website or application.

free open api awe.sm


20. YouTube API

Helps you add YouTube functionality to your sites and apps. For example, you can use an embedded player into your app, enable users to subscribe in one click, and schedule and manage live broadcasts.

21. LinkedIn API

With this API, you can add LinkedIn functionality to your sites and apps such as signing in and sharing on LinkedIn.

22. Vimeo API

The Vimeo API is a great choice when you want to add videos within your app and customize the playback experience. You can also take advantage of Vimeo's video tools.

23. Twitter API

Helps you read and write Twitter data, which can be helpful for building scheduling apps and other productivity functionality.

24. Facebook API

Helps you read and write Facebook data and/or manage your Facebook marketing activities.

25. New York Times

When you need to know what’s happening around the world, use the New York Times API to pull any article, list, bestseller, tag, movie review, or other popular shared content.

26. NASA

You can access the NASA data portal, visualizations, APIs, and more using the NASA API.

free open api nasa


27. Mashape for APIs

Lastly is the API for APIs — a marketplace for APIs. With the Mashape API, you can discover any API you need.

The Best Open APIs for Marketers & Content Developers

These options represent some of the best free open APIs that marketers and content developers can use to make their work easier and more enjoyable. Use this list to improve your next project, campaign, blog post, or website.

Editor's note: This post was originally published in March 2020 and has been updated for comprehensiveness.

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Originally published Dec 8, 2020 7:00:00 AM, updated December 08 2020


Application Programming Interface (API)