Xampp SSL Certificate Creator for Windows (advanced version of https://shellcreeper.com/how-to-create-valid-ssl-in-localhost-for-xampp/)

cert-template.conf

[ req ]

default_bits        = 2048
default_keyfile     = server-key.pem
distinguished_name  = subject
req_extensions      = req_ext
x509_extensions     = x509_ext
string_mask         = utf8only

[ subject ]

countryName                 = Country Name (2 letter code)
countryName_default         = US

stateOrProvinceName         = State or Province Name (full name)
stateOrProvinceName_default = NY

localityName                = Locality Name (eg, city)
localityName_default        = New York

organizationName            = Organization Name (eg, company)
organizationName_default    = Example, LLC

commonName                  = Common Name (e.g. server FQDN or YOUR name)
commonName_default          = {{DOMAIN}}

emailAddress                = Email Address
emailAddress_default        = test@example.com

[ x509_ext ]

subjectKeyIdentifier   = hash
authorityKeyIdentifier = keyid,issuer

basicConstraints       = CA:FALSE
keyUsage               = digitalSignature, keyEncipherment
subjectAltName         = @alternate_names
nsComment              = "OpenSSL Generated Certificate"

[ req_ext ]

subjectKeyIdentifier = hash

basicConstraints     = CA:FALSE
keyUsage             = digitalSignature, keyEncipherment
subjectAltName       = @alternate_names
nsComment            = "OpenSSL Generated Certificate"

[ alternate_names ]

DNS.1       = {{DOMAIN}}

make-cert.bat

@echo off
set /p domain="Enter Domain: "
set OPENSSL_CONF=../conf/openssl.cnf

REM
REM Read the "cert-template.conf" file and replace all {{DOMAIN}} placeholders by the entered domain.
REM Write the result into a new file called "cert.conf".
REM
REM @see https://stackoverflow.com/questions/5273937/how-to-replace-substrings-in-windows-batch-file#20227248
REM
setlocal enabledelayedexpansion
set INTEXTFILE=cert-template.conf
set OUTTEXTFILE=cert.conf
set SEARCHTEXT={{DOMAIN}}
set REPLACETEXT=%domain%

if exist %OUTTEXTFILE% del /F %OUTTEXTFILE%
for /f "tokens=1,* delims=¶" %%A in ( '"findstr /n ^^ %INTEXTFILE%"') do (
   SET string=%%A
   for /f "delims=: tokens=1,*" %%a in ("!string!") do set "string=%%b"
   if  "!string!" == "" (
       echo.>>%OUTTEXTFILE%
   ) else (
      SET modified=!string:%SEARCHTEXT%=%REPLACETEXT%!
      echo !modified! >> %OUTTEXTFILE%
  )
)


REM
REM Create the target directory.
REM
if not exist .\%domain% mkdir .\%domain%


REM
REM Create the certificate and key files.
REM
..\bin\openssl req -config %OUTTEXTFILE% -new -sha256 -newkey rsa:2048 -nodes -keyout %domain%\server.key -x509 -days 365 -out %domain%\server.crt


REM
REM Delete the written file "cert.conf" as this file would only be used to create the certificate.
REM
if exist %OUTTEXTFILE% del /F %OUTTEXTFILE%


echo.
echo -----
echo The certificate was provided.
echo.
pause