You need to configure your site keys by adding your public and private keys.

    For version 9

    You can configure the settings in the appSettings.json file:

    "Forms": {
      "FieldTypes": {
        "Recaptcha3": {
            "SiteKey": "",
            "PrivateKey": ""

    For version 8.x and below

    You can configure your public and private keys in the UmbracoForms.config file located in ~/App_Plugins/UmbracoForms/:

    <setting key="RecaptchaV3SiteKey" value="..." />
    <setting key="RecaptchaV3PrivateKey" value="..." />

    reCAPTCHA v2

    You can create your keys by logging into your reCAPTCHA account.

    Ensure to select the Mandatory field while adding the Recaptcha2 to your Form.