Custom Captcha Field for Fluent Forms

Adds a “Custom Captcha” field to the Fluent Forms editor with three challenge types:

• Image captcha — a 6-character code rendered as an image, with customizable text color and a transparent background by default so it blends with any form design
• Math captcha — a simple arithmetic question rendered as an image
• Question and answer — you define the question (field label) and the expected answer

Challenges are single-use and expire after 15 minutes. Answers are stored server-side via WordPress transients — nothing is exposed to the browser except the image itself. Visitors get a refresh button to request a new challenge, and the captcha automatically renews after each AJAX submission, so it also works on cached pages.

On top of the captcha you get two extra spam defenses:

• Time-trap (optional, off by default) — submissions completed faster than a human possibly could are rejected via an HMAC-signed timestamp; enable it and set the minimum submit time per field
• Disposable email blocking (optional, on by default) — rejects submissions where an email field uses a temporary/disposable email domain like mailinator.com or yopmail.com; extend the list with the ffc_captcha_blocked_email_domains filter

Everything runs on your own server: no external captcha service, no API keys, no cookies, no visitor data sent anywhere.

Requirements

Fluent Forms is required. The PHP GD extension is recommended for image rendering (with a plain-text fallback when unavailable).

How To Use

1. Activate the plugin
2. Edit a form in Fluent Forms — a new “Custom Captcha” field appears in the editor
3. Drop it into your form and pick the captcha type in the field settings
4. Optionally set the text color, background color (RGB values like “68, 68, 68”, or “transparent”) and error message