Dropwizard's configuration is specified in yaml by default. While yaml has nice properties, you may prefer json or some other format.Dropwizard's https://www.dropwizard.io/en/latest/manual/core.html#configuration documentation claims:If your configuration file doesn't end in .yml or .yaml, Dropwizard tries to parse it as a JSON file.This is easily disproved by renaming example.yml to example.json and trying to run the application. It will incorrectly start without error.Since json syntax is a subset of yml syntax, you can go ahead and convert your configuration file to json without changing the file extension from yaml or yml. However, this approach doesn't prevent you from accidentally using yaml syntax.You can change your application to use json for its configuration using JsonConfigurationFactoryFactory . java @Override public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) { bootstrap.setConfigurationFactoryFactory(new JsonConfigurationFactoryFactory<>()); // ... } JsonConfigurationFactoryFactory uses json5 syntax by default, using optional features in Jackson. So you'll still be able to include comments inside your configuration files.After adding the bundle, you'll have to convert your configuration files to json5 and rename them. So example.yml becomes example.json5 . Configuration files used in DropwizardAppRule / DropwizardAppExtension tests must be converted as well. So src/test/resources/test-example.yml becomes src/test/resources/test-example.json5

JsonConfigurationFactoryFactory lives in the liftwizard-configuration-factory-json module. xml <dependency> <groupId>io.liftwizard</groupId> <artifactId>liftwizard-configuration-factory-json</artifactId> </dependency>