On Windows

In this chapter, we’ll demonstrate how to install RESTCaptcha on Windows Server 2025 using IIS 10 as the hosting environment. All steps are performed using PowerShell.

Installing IIS

Open PowerShell as an administrator and check whether IIS 10 is already installed:

Get-WindowsFeature -Name Web-Server, Web-Scripting-Tools

If the result looks like this, you’re good to go and can proceed straight to the next section, “Installing ASP.NET”:

Display Name                                            Name                       Install State
------------                                            ----                       -------------
[X] Web Server (IIS)                                    Web-Server                     Installed
        [X] IIS Management Scripts and Tools            Web-Scripting-Tools            Installed

If one of these components is missing, install the Windows features manually:

Install-WindowsFeature -Name Web-Server, Web-Scripting-Tools

Then check whether you can access the IIS 10 default website locally:

Invoke-WebRequest -Uri "http://localhost" -UseBasicParsing

IIS default website

The default IIS 10 website is not required for RESTCaptcha. You can—and should—disable it:

Import-Module WebAdministration
Stop-Website -Name "Default Web Site"
Set-ItemProperty "IIS:\Sites\Default Web Site" serverAutoStart False

Installing ASP.NET

RESTCaptcha requires the ASP.NET framework as a dependency.

Open PowerShell as an administrator and run the following command to install the ASP.NET Core 9.0 Runtime – Windows Hosting Bundle:

winget install --id=Microsoft.DotNet.HostingBundle.9 -e --accept-package-agreements --accept-source-agreements

Installing RESTCaptcha

Copying the binaries

Create a new folder for RESTCaptcha (for example, C:\Sites\RestCaptcha) and copy the binaries from the latest release into it. The following PowerShell one-liner does this automatically:

$r=Invoke-RestMethod "https://api.github.com/repos/openpotato/restcaptcha/releases/latest" -Headers @{ "User-Agent"="PS" };$a=$r.assets|?{ $_.name -like "*.zip"}|select -f 1;$zip="$env:TEMP\$($a.name)";Invoke-WebRequest $a.browser_download_url -OutFile $zip -Headers @{ "User-Agent"="PS" };Expand-Archive $zip -DestinationPath "C:\Sites\RestCaptcha" -Force;Remove-Item $zip

Copy the appsettings.json file within this folder and rename it to appsettings.Production.json:

Copy-Item C:\Sites\RestCaptcha\appsettings.json C:\Sites\RestCaptcha\appsettings.Production.json

Modify the contents of appsettings.Production.json as follows:

{
  "Serilog": {
    "Using": [
      "Serilog.Sinks.Console",
      "Serilog.Sinks.File"
    ],
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft.AspNetCore": "Warning",
        "Microsoft.AspNetCore.Hosting.Diagnostics": "Warning",
        "Microsoft.AspNetCore.HttpLogging.HttpLoggingMiddleware": "Information"
      }
    },
    "WriteTo": [
      { "Name": "Console" },
      {
        "Name": "File",
        "Args": {
          "path": "c:\\Sites\\RestCaptcha\\logs\\log-.txt",
          "rollingInterval": "Day",
          "retainedFileCountLimit": 7,
          "fileSizeLimitBytes": 10000000,
          "rollOnFileSizeLimit": true
        }
      }
    ]
  },
  "RestCaptcha": {
    "Sites": [
      {
        "name": "My Site",
        "description": "My site using RESTCaptcha",
        "siteKey": "My-Site-Key",
        "siteSecret": "AeyGWx3kQeyrDFCE5KDR",
        "validHostNames": []
      }
    ]
  }
}

Creating a new IIS site

First, load the IIS Management Module into your PowerShell session:

Import-Module WebAdministration

Next, create a dedicated IIS App Pool for the ASP.NET service and configure it:

New-WebAppPool -Name "AspNetCorePool"
Set-ItemProperty "IIS:\AppPools\AspNetCorePool" -Name managedRuntimeVersion -Value ""
Set-ItemProperty "IIS:\AppPools\AspNetCorePool" -Name enable32BitAppOnWin64 -Value False

Now create a new IIS Site pointing to your RESTCaptcha folder C:\Sites\RestCaptcha:

New-Item "IIS:\Sites\RestCaptcha" `
   -bindings @(
     @{protocol="http";  bindingInformation="*:8080:"},
     @{protocol="https"; bindingInformation="*:443:captcha.example.com"}
   ) `
   -physicalPath "C:\Sites\RestCaptcha"
Set-ItemProperty "IIS:\Sites\RestCaptcha" -Name applicationPool -Value "AspNetCorePool"

You now have two bindings: a local HTTP binding on port 8080 and a public HTTPS binding on port 443.

In the folder C:\Sites\RestCaptcha, create a new file named web.config and insert the following XML:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <handlers>
      <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
    </handlers>
    <aspNetCore processPath="dotnet"
                arguments=".\RestCaptcha.WebService.dll"
                stdoutLogEnabled="false"
                stdoutLogFile=".\logs\stdout"
                hostingModel="inprocess">
      <environmentVariables>
        <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Production" />
      </environmentVariables>
    </aspNetCore>
  </system.webServer>
</configuration>

The web.config file configures RESTCaptcha as an ASP.NET application, defining how incoming requests are handled. In this case, RESTCaptcha runs within the IIS worker process (in-process hosting model).

That completes the basic configuration. Restart your IIS site:

Restart-WebAppPool "AspNetCorePool"; 
Restart-WebItem "IIS:\Sites\RestCaptcha"

You can now test the RESTCaptcha health endpoint locally:

Invoke-WebRequest -Uri "http://localhost:8080/health" -UseBasicParsing

For public access, you still need a TLS certificate for your HTTPS binding. A good option is to use Let’s Encrypt to generate free TLS certificates.

To do this, install an ACME client. One of the best for Windows is simple-acme. Install and run the command-line tool — once you’ve answered the prompts, simple-acme will communicate with Let’s Encrypt, request a TLS certificate for the domain captcha.example.com, and configure it automatically.

A test in your web browser at https://captcha.example.com/health should now work successfully.