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Text reCaptcha Validation, a computer program or system intended to distinguish human from machine input, typically as a way of thwarting spam and automated extraction of data from websites

Slider Captcha for Outsystems app, based on https://www.jqueryscript.net/form/image-puzzle-slider-captcha.html and https://github.com/ArgoZhang/SliderCaptcha

Block spam submission from bad bots using Honeypot anti-spam technique: This demo component shows how you can prevent bot spam submissions without using Captcha or 3rd party tools. Use the simple method on submit action and get free from spam submissions. 

One can use this captcha in their web app and can get whether entered is valid or not.

ALTCHA is a free, open-source CAPTCHA alternative that protects your website from spam and abuse.

ALTCHA uses a proof-of-work mechanism to protect your website, APIs, and online services from spam and unwanted content. Unlike other CAPTCHA solutions, ALTCHA is free, open-source and self-hosted, does not use cookies nor fingerprinting, does not track users, and is fully compliant with GDPR.