By default Spring uses 0 indexed page meaning a page number of 0 in the request equals the first page.

You can customize this to start from 1 in following by creating a bean of PageableHandlerMethodArgumentResolverCustomizer and setting the setOneIndexedParameters to true.

You can read  more about the method argument resolver and other customizations to pagable in my earlier blog post:  https://ganeshtiwaridotcomdotnp.blogspot.com/2020/09/spring-data-pagination-set-max-page.html

Configures whether to expose and assume 1-based page number indexes in the request parameters. When its true, a page number of 1 in the request will be considered the first page.

@Bean
public PageableHandlerMethodArgumentResolverCustomizer paginationCustomizer() {
  return pageableResolver -> {
     pageableResolver.setOneIndexedParameters(true); //default is false, starts with 0
  };
}

Now you can have your pagination url to start with page=1 eg: /users?size=20&page=1.