# CAPTCHA alternatives

**URL:** <https://forums.knack.com/t/captcha-alternatives/17862>\
**Category:** Get Answers\
**Created:** [September 8, 2024, 2:50pm UTC](https://forums.knack.com/t/captcha-alternatives/17862 "2024-09-08T14:50:15Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Bradley](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Bradley](https://forums.knack.com/u/Bradley)\
**Post date:** [September 8, 2024, 2:50pm UTC](https://forums.knack.com/t/captcha-alternatives/17862/1 "2024-09-08T14:50:15Z")

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Has anyone here used a CAPTCHA alternative for Knack? The issue is that for most you need a TXT file on the DNS and Knack uses its own servers, so it won’t work

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**Author:** ![ivan](https://sea2.discourse-cdn.com/flex020/user_avatar/forums.knack.com/ivan/32/1019_2.png) [@ivan](https://forums.knack.com/u/ivan)\
**Post date:** [December 16, 2025, 3:51am UTC](https://forums.knack.com/t/captcha-alternatives/17862/2 "2025-12-16T03:51:10Z")

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Hi Bradley, if you’re dealing with bot spam on public Knack forms, here’s a simple alternative that requires no external integrations:

Add a custom validation question to your form that only accepts a specific answer. For example:

 ![image](https://us1.discourse-cdn.com/flex020/uploads/knack/original/2X/0/0401eeb19350d50e76ef7d3674100f9334b6e029.png)

Then set a field-level validation rule that only allows the correct value (in this case, “3”).

**Why this works:** Most spam bots auto-fill form fields with random data and can’t parse natural language or perform simple calculations. This stops the majority of generic bot submissions.

**Limitations:** This won’t stop sophisticated AI-powered bots, but it’s effective against the common automated spam most public forms receive. If you need stronger protection, a CAPTCHA solution outside of Knack would be the next step.

It’s a quick, no-cost solution worth trying before investing in more complex alternatives.