> For the complete documentation index, see [llms.txt](https://docs.ngsurvey.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ngsurvey.com/form-management/form-designer/answers/answer-types/captcha.md).

# Captcha

The captcha answer type will protect your survey against unwanted automated answers from bots. 

![](https://1025048312-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M8fLhS0bmfBRyq0HdUm%2F-MBy4b-tXZfmMOm9MbWX%2F-MBy5QAqrgGz83CriyXa%2Fimage.png?alt=media\&token=0077d91e-3cbd-4654-9ed2-42a910a6dd8d)

## 🔅 Captcha properties

You may configure additional captcha properties from the [answer properties](/form-management/form-designer/answers/answer-properties.md) page.

* **`Size`** set the size of the captcha from normal to invisible.
* **`Theme`** color theme used to render the captcha.
* **`Google's recaptcha site key`** your personal [site key](/installation-setup/system-settings/google/captcha.md). 
* **`Google's recaptcha secret key`** your personal [secret key](/installation-setup/system-settings/google/captcha.md) 
* **`Google recaptcha URL`** [verification URL](/installation-setup/system-settings/google.md) of the captcha 
* **`Expires after`** minutes after which  the authorization of the captcha is not valid anymore and requires the respondent to re-confirm. 

{% hint style="warning" %}
It requires to have setup the Google captcha settings in your ngSurvey [settings](/installation-setup/system-settings/google.md) or from the [answer properties](/form-management/form-designer/answers/answer-properties.md).
{% endhint %}


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```
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```

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