With the rise of Artificial Intelligence, it is more important than ever for application developers to be able to determine if a user is a human or a machine. Enter CAPTCHA, which is an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart". CAPTCHAS, which come in a variety of shapes and sizes, are designed to decrease spam and malicious activity. The most common CAPTCHA would be a series of random alphanumeric characters displayed on a web page in which a human must copy into a web form.

Developers looking to add a CAPTCHA function, or a CAPTCHA-solving function, to applications would need an Application Programming Interface, or API, to accomplish these tasks. The best place to find one is the CAPTCHA category on ProgrammableWeb. Dozens of APIs, including several services that recognize and bypass CAPTCHAs, are available there.

In this article we highlight the most popular APIs for CAPTCHA, as chosen by the number of page visits on ProgrammableWeb.

1. CAPTCHAs.IO API

CAPTCHAs.IO (https://captchas.io) is an automated captcha recognition service that supports more than 30,000 image captchas, audio captchas, and reCAPTCHA v2 and v3, including invisible reCAPTCHA. The CAPTCHAs.IO APITrack this API provides RESTful access to all of CAPTCHAs.io's captcha-solving methods. Developers can choose to get API responses in either JSON or plain text.

2. Death By CAPTCHA API

Death By CAPTCHA offers a CAPTCHA bypass service. Users pass captchas through the APITrack this API where they are solved by an OCR or manually. The solved CAPTCHA is then passed back where it can be used. The API has an average solved response time of 15 seconds, and an average accuracy rate of 90%.

3. Anti Captcha API

Anti Captcha is a human powered CAPTCHA solving service. The Anti Captcha APITrack this API integrates authentication solutions into applications via HTTP POST and API Key. Resources allow to upload CAPTCHA & receive ID, request, & receive captcha responses.

4. AZcaptcha

AZcaptcha is a automatic image and CAPTCHA recognition service. The AZcaptcha APITrack this API's main purpose is solving CAPTCHAs in a quick and accurate way by AI employees, but the service is not limited only to CAPTCHA solving. You can convert to text any image that a AI can recognize.

5. ProxyCrawl API

ProxyCrawl combines artificial intelligence with a team of engineers to bypass crawling restrictions and captchas and provide easy access to scraping and crawling websites around the internet. The ProxyCrawl APITrack this API allows developers to scrape any website using real web browsers. This means that even if a page is built using only JavaScript, ProxyCrawl can crawl it and provide the HTML necessary to scrape it. The API handles proxy management, avoids captchas and blocks, and manages automated browsers.

6. Solve Recaptcha API

The Solve Recaptcha APITrack this API automatically solves Google's reCAPTCHA2 CAPTCHAs via data-site key. The API is fee-based depending on the number of threads per month.

7. Google reCAPTCHA API

Google reCAPTCHA v3 APITrack this API is a CAPTCHA implementation that distinguishes humans from computers without user interactive tests. reCAPTCHA works via a machine learning-based risk analysis engine and determines a user validity score. This API is accessed indirectly from the Javascript SDK.

8. Captcha Solutions API

Captcha Solutions is a CAPTCHA decoding web service offering solutions based on a flat rate per CAPTCHA solved. This RESTful Captcha Solutions APITrack this API is designed to solve a large variety of a CAPTCHA challenges for a broad spectrum of applications.

9. 2Captcha API

2Captcha provides human-powered image and CAPTCHA solving services. The 2Captcha API returns data of human-powered image recognition to authorize online users. With the API, developers can apply an available algorithm that includes sending an image to a server, obtaining the ID of the picture, beginning the cycle that checks if the CAPTCHA is solved, and confirming if the answer is correct.

10. Captcha.guru API

The Captcha.guru APITrack this API provides reCAPTCHA and antiCAPTCHA services. With the API, developers can use an image that contains distorted but human-readable text. To solve the CAPTCHA, the user has to type the text from the image. The API supports JSON formats. API Keys are required to authenticate.