EU CAPTCHA for .NET Core
.NET Core is a cross-platform, open-source successor to the .NET Framework, designed for building modern, high-performance applications across Windows, Linux, and macOS. Add GDPR-compliant bot protection to your .NET Core applications with a privacy-first, EU-hosted CAPTCHA solution.
Why choose Myra EU CAPTCHA?
Interaction-free user experience
No puzzles, no clicks – invisible bot protection with zero user friction.
Digital sovereignty made in Germany
Fully GDPR-compliant, no cookies, no tracking – developed and hosted in Germany.
Intelligent threat detection
Smart protection trained by more than 100 billion daily Myra CDN signals.
Proven technology
Over 5 billion successfully secured authentication attempts.
How the integration works
1. Create an EU CAPTCHA account
Creating an account is completely free, all you need is a valid email address and you’re ready to go. Choose a plan that covers your needs. The first 3 months are free of charge.
Create an Account2. Create a sitekey
Create a sitekey in the EU CAPTCHA dashboard for the domain you want to protect. Provide a clear label so you can easily identify it later. This sitekey links the widget on your .NET Core application to your EU CAPTCHA account.
3. Add EU CAPTCHA to your form
Load verify.js and place the EU CAPTCHA widget div with your sitekey inside any HTML form you want to protect — the response token is automatically included on submission.
View HTML integration guide4. Verify the token in your .NET backend
In your ASP.NET Core controller, minimal API handler, or middleware, inject the HTTP client and validate the eu-captcha-response token against the EU CAPTCHA API before processing any submission.
View server-side verification guide
5. The EU CAPTCHA widget will appear on your form.
Frequently Asked Questions
How do I verify a CAPTCHA token in .NET Core?
Register a typed HttpClient in your DI container for the EU CAPTCHA API. In your controller action, minimal API endpoint, or middleware, inject the client and POST the eu-captcha-response token with your secret key to the EU CAPTCHA verification endpoint. Process the form data only if the response confirms a valid human interaction.
Does EU CAPTCHA work with ASP.NET Core Minimal APIs?
Yes. In a Minimal API, inject the typed HttpClient as a parameter in your endpoint delegate or via dependency injection. Read the eu-captcha-response from the form or JSON body, call the EU CAPTCHA verification endpoint, and return a Results.BadRequest() or Results.UnprocessableEntity() if verification fails before executing the endpoint's business logic.
How do I use IHttpClientFactory to call the EU CAPTCHA API in .NET?
Register a typed or named HttpClient in Program.cs using builder.Services.AddHttpClient. Configure the base address to the EU CAPTCHA verification endpoint. Inject the IHttpClientFactory or the typed client into your service or controller, call PostAsync with your secret key and the token in the request body, and parse the JSON response to determine the verification result.
Can EU CAPTCHA be used with Blazor forms?
Yes. For Blazor Server and Blazor WebAssembly, include the EU CAPTCHA widget div in your Razor component markup by rendering it inside a standard HTML form or using JavaScript interoperability. Read the token via JS interop and pass it to your Blazor service or HttpClient call for server-side verification against the EU CAPTCHA API.
How do I store the EU CAPTCHA secret key securely in .NET Core?
Use the .NET secrets management system. For development, store the key in user secrets via dotnet user-secrets set. For production, use environment variables, Azure Key Vault bound through the Microsoft.Extensions.Configuration.AzureKeyVault package, or AWS Systems Manager Parameter Store. Read it in code using IConfiguration['EuCaptcha:SecretKey'] and inject it via the options pattern.
Is EU CAPTCHA compatible with .NET 8 and .NET 9?
Yes. EU CAPTCHA verification requires only a standard HTTPS POST request to the API endpoint, which is fully supported by HttpClient in all .NET versions. The integration works with .NET 6, 7, 8, and 9, including the latest minimal hosting model and trimming-compatible deployments.
Is EU CAPTCHA GDPR compliant for .NET Core 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 device or browser information) in line with the GDPR. Your organization remains responsible for providing transparent privacy information, selecting an appropriate legal basis, and obtaining any required consent for your specific .NET implementation. This information does not constitute legal advice; please consult your legal counsel for an assessment of your individual case.
Ready for a better CAPTCHA?
Experience invisible bot protection with privacy‑first, GDPR‑compliant verification made and hosted in Germany. Try Myra EU CAPTCHA now 3 months for free and secure your web forms without adding friction for your users.
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