EU CAPTCHA for Node.js

Frequently Asked Questions

• How do I verify a CAPTCHA token in Node.js?

  Make a POST request to the EU CAPTCHA verification API from your Node.js handler using axios, node-fetch, or the built-in https module. Send your secret key and the eu-captcha-response token received from the form. If the API returns a successful verification, process the form data. Otherwise, return an appropriate error to the client.

• Does EU CAPTCHA work with Express.js?

  Yes. EU CAPTCHA integrates cleanly with Express.js. Create a verification middleware or inline handler that reads the eu-captcha-response from req.body and calls the EU CAPTCHA API. If verification fails, return a 400 response before your business logic runs. You can also create a reusable middleware and attach it to any route that receives form data.

• How do I integrate EU CAPTCHA with Fastify or Koa?

  The integration pattern is the same regardless of the Node.js framework. In Fastify, add verification logic inside a preHandler hook or directly in your route handler. In Koa, use a middleware function that calls the EU CAPTCHA API and either calls next() on success or returns an error response. The EU CAPTCHA API call is a standard HTTPS POST request that works with any HTTP client.

• Is there a Node.js module for EU CAPTCHA?

  Yes. EU CAPTCHA provides an official Node.js client via the OpenAPI generator. Install it to get a typed client that abstracts the HTTP call and handles error parsing. Alternatively, you can call the EU CAPTCHA REST API directly using any HTTP client library in your Node.js project without any additional SDK.

• Can I implement EU CAPTCHA token verification as Express middleware?

  Yes. Creating a reusable Express middleware is the recommended pattern for protecting multiple routes. The middleware reads the eu-captcha-response value from req.body, calls the EU CAPTCHA API, and either calls next() to pass control to the route handler on success, or returns a 422 response with an error message on failure.

• How do I handle verification errors in a Node.js API?

  If the EU CAPTCHA API returns a failed verification, return an appropriate HTTP error to the client — typically 400 Bad Request or 422 Unprocessable Entity — with a message indicating that the bot check failed. For network errors or timeouts when calling the EU CAPTCHA API, EU CAPTCHA provides a failsafe mode that allows submissions to proceed so your application remains available.

• Is EU CAPTCHA GDPR compliant for Node.js applications?

  Yes. EU CAPTCHA is operated by an EU-based company, is hosted entirely in Germany, and does not rely on US cloud providers or infrastructure subject to US surveillance laws. The service processes only the data necessary to provide and verify the CAPTCHA (such as IP address and technical browser or device information) in line with the requirements of the GDPR. Your organization remains responsible for providing transparent privacy information, selecting an appropriate legal basis, and obtaining any required consent for your specific Node.js implementation. This information does not constitute legal advice; please consult your legal counsel for an assessment of your individual case.