EU CAPTCHA for Go

Frequently Asked Questions

• How do I verify a CAPTCHA token in Go?

  Install the EU CAPTCHA Go client using go get. In your HTTP handler, read the eu-captcha-response value from r.FormValue or the parsed request body, then call the client's Verify function with your secret key and the token. If verification succeeds, proceed with request processing. Otherwise, return an appropriate HTTP error response.

• Does EU CAPTCHA work with Gin or Echo?

  Yes. EU CAPTCHA works with Gin, Echo, Chi, and any Go HTTP framework. In Gin, create a middleware function that reads the token from c.PostForm, calls the EU CAPTCHA client, and either calls c.Next() or aborts with c.AbortWithStatus. In Echo, implement a middleware that wraps the handler and performs verification before calling next(c).

• Is there an official Go client for EU CAPTCHA?

  Yes. EU CAPTCHA provides an official Go client generated from the OpenAPI specification. Install it via go get from the EU CAPTCHA repository. The client is idiomatic Go code that provides a typed interface for calling the verification API, handling errors, and parsing responses.

• How do I implement EU CAPTCHA verification as Go middleware?

  Create a middleware function with the signature func(http.Handler) http.Handler. Inside, read the eu-captcha-response from the request form data or body, call the EU CAPTCHA client to verify it, and either call the next handler on success or write an http.StatusBadRequest response and return on failure. Apply this middleware to any router group that receives form submissions.

• Can I use EU CAPTCHA with Go's standard net/http package?

  Yes. EU CAPTCHA works with Go's standard library net/http without any additional framework. In an http.HandlerFunc, parse the form with r.ParseForm(), read r.FormValue('eu-captcha-response'), and call the EU CAPTCHA client. The client itself uses standard net/http internally for the API call.

• How do I store the EU CAPTCHA secret key securely in a Go application?

  Store your secret key as an environment variable and read it at startup with os.Getenv. Never hardcode it in your source code. For production deployments, use a secrets management solution such as HashiCorp Vault, AWS Secrets Manager, or Kubernetes secrets. Pass the key to your verification handler via dependency injection or a configuration struct.

• Is EU CAPTCHA GDPR compliant for Go web 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 Go implementation. This information does not constitute legal advice; please consult your legal counsel for an assessment of your individual case.