Using Shield silentCAPTCHA with Gravity Forms Zero Spam
Gravity Forms Zero Spam can use Shield Security’s silentCAPTCHA as an additional spam check for your forms. silentCAPTCHA is the invisible bot-detection technology built into the free Shield Security plugin: it evaluates each submission for signs of automation in the background, without showing your visitors any puzzles, checkboxes, or extra steps. When Shield identifies a submission as coming from a bot, Zero Spam marks the entry as spam.
The integration runs entirely server-side. No field needs to be added to your forms, and nothing changes for your visitors.
Installing Shield Security #
The integration requires the free Shield Security plugin. Go to Plugins > Add New, search for “silentCAPTCHA”, then install and activate the first result, Shield Security.
Note: While Shield is not active, the silentCAPTCHA settings in Zero Spam are disabled and show an unavailability notice. Your saved settings are kept and take effect again once Shield is back.
Enabling silentCAPTCHA for your forms #
There are two settings: a global default and a per-form override.
Global default: go to Forms > Settings > Zero Spam and turn on “Enable Shield silentCAPTCHA by Default”. Forms that don’t have their own Shield setting will use this default.
Per-form: in the Spam Detection section of the form’s settings (Form Options on Gravity Forms versions older than 2.9.21), the “Enable Shield silentCAPTCHA for this form” toggle appears right below the “Prevent spam using Gravity Forms Zero Spam” setting. A form without its own saved setting follows the global default. Once you save the form’s settings, the form’s own value takes over.
Note: The “Prevent spam using Gravity Forms Zero Spam” setting is the master switch for all of the plugin’s spam checks on that form. When it’s off, the token check, Shield silentCAPTCHA, and AI Spam Review are all disabled for that form. Likewise, when “Enable Zero Spam by Default” is set to Disabled in the global plugin settings, all spam checks are turned off for every form, including forms whose own setting is turned on.
If Shield’s bot threshold is set to 0, silentCAPTCHA will not flag any submissions. Zero Spam shows a warning below the setting when this is the case.
What happens when a submission is flagged #
Entries flagged by silentCAPTCHA are marked as spam and appear under Forms > Entries in the Spam filter, with an entry note listing Shield silentCAPTCHA as the reason the entry was flagged. As with Zero Spam’s other checks, notifications and add-on feeds are not processed for entries marked as spam.
The integration is designed to never get in the way of legitimate submissions: if Shield is deactivated, misconfigured, or returns an error, submissions are not blocked, and Zero Spam’s other checks continue to run normally.
Choosing the order of spam checks #
The Zero Spam settings page also includes a “Spam Check Order” section where you can choose the order in which the plugin’s spam checks run: the Zero Spam token check, Shield silentCAPTCHA, and AI Spam Review. Checks that are unavailable (for example, Shield silentCAPTCHA while Shield Security is inactive) keep their position and are skipped.
The “Stop after first detection” toggle, enabled by default, skips the remaining checks once a check flags a submission as spam. When disabled, every check still runs and records its verdict as a note on the entry; a flagged submission is never restored by a later check.
Learn more about silentCAPTCHA #
The integration was contributed by Shield Security developer Paul Goodchild. Shield’s own documentation covers how silentCAPTCHA works in more detail: Shield silentCAPTCHA Integration on the Shield Security Knowledge Base.
