What is spring-validation-plus?

Spring Validation Plus is a Java library that adds a large set of extra rules for checking whether user submitted data is valid, built on top of Jakarta Validation, which is the standard validation system already built into Spring Boot. The standard system only ships around 22 basic rules, like checking that a field is not null or that a number is within a range. This project adds more than 85 additional rules inspired by how the PHP framework Laravel handles validation, things that Jakarta Validation does not cover on its own. The added rules cover several gaps. There are rules that compare multiple fields against each other, for example requiring a password confirmation field to match the password, or making one field required only if another field is filled in. There are rules that check a database, such as confirming an email address is not already used by another account, though those specific rules require your project to already use JPA, a common way Java talks to databases. There are also format checks for things like email addresses, URLs, and JSON strings, plus rules for handling optional fields cleanly. Another focus of the project is making validation errors easier to work with. Instead of scattered, technical sounding messages, errors come back as a single organized JSON structure grouped by field name, and messages are already translated into Spanish, English, and Portuguese. Type mismatches, like sending text where a number was expected, are turned into plain error messages instead of low-level exceptions. To use it, a Spring Boot project just adds one dependency, the Validation Plus starter, which already bundles the underlying validation engine so nothing else needs to be installed for the core features. Database-related rules like checking for existing or unique values are the one exception, since those need the JPA dependency added separately. The library works with both Spring Boot 3 and Spring Boot 4, requires Java 17 or newer, and is released under the Apache 2.0 license. The full README is longer than what was shown.