General & Architecture
What is the required technology stack?
AppJars are Java libraries for the Spring Boot ecosystem.
- Java: Requires Java 21 or later.
- Spring Boot: Requires Spring Boot 4.1.x or later.
- Vaadin: Required for components that include a UI layer; compatible with Vaadin 25.2 and later. If you are only using the backend or service layer of an AppJar, Vaadin is not required.
Do I have to adopt everything at once, or can I use AppJars independently?
You can pick and choose. AppJars are designed as independent “building blocks,” so you adopt only the functionality you need and leave the rest out. Each AppJar is made up of several Maven modules that you add to your project as dependencies.
Do AppJars phone home or send telemetry?
No. AppJars do not phone home or send telemetry. They run entirely inside your own application and require no network communication with our servers to operate.
Is the source code available?
Yes. The source is available so you can attach it in your IDE to read and step through the code while debugging your own application.
Integration & Database
How is the database schema managed? Do you provide SQL scripts?
We provide standard JPA Entities. We do not force specific SQL scripts or Liquibase changelogs because naming strategies vary significantly between projects. We recommend configuring your ORM (e.g., Hibernate) to handle the schema generation or validation during your development process based on the provided entities.
Does it support my database engine?
Since we use standard JPA (Java Persistence API), AppJars are database-agnostic. They support any relational database compatible with Hibernate, such as PostgreSQL, MySQL, Oracle, SQL Server, and MariaDB.
Free Mode
Is there a free mode?
Yes. Without any paid license, AppJars run in free mode, which gives you core functionality within certain usage limits. This lets you add an AppJar to a real project and evaluate it before committing.
Can I use free mode in production?
Yes, as long as you stay within the free-mode usage limits.