Adding Template Helpers

Extensions that implement the TemplateHelperProviderExtension interface provide additional Handlebars helpers to the templating system:

new WireMockServer(wireMockConfig().extensions(
    new TemplateHelperProviderExtension() {
        public String getName() {
            return "custom-helpers";

        public Map<String, Helper<?>> provideTemplateHelpers() {
            Helper<String> helper = (context, options) -> context.length();
            return Map.of("string-length", helper);

This custom string-length helper will return the string length of the supplied parameter and is used like this:

{{string-length 'abcde'}}
{{string-length request.body}}