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Developer docs

CrossFly Core documentation

Everything you need to build native cross-platform apps in Java with CrossFly Core — from your first window to shipping on every platform.

Install CrossFly and get your first app running — from zero to desktop in minutes.

A guided, sequential course that builds a complete app while teaching every CrossFly fundamental.

The canonical explanation of the why behind CrossFly: architecture, component model, rendering pipeline, paint thread, layout and lifecycle.

Guide + Reference for building screens in CrossFly: widgets, layouts, navigation, themes, animations, images/graphics and forms.

State, persistence (SQLite), networking and device integrations (camera, GPS, Bluetooth BLE, biometrics, maps) in CrossFly.

Short, to-the-point recipes by task — "how to do X" in CrossFly, with minimal code and links to go deeper.

Doing it right at scale in CrossFly — responsiveness, performance, architecture, testing, accessibility, errors and security, with the reasoning.

Per-platform guide (Desktop/LWJGL3, Android, iOS/RoboVM, Web/TeaVM) to build, run and publish the same Java app on each of them.

Translation tutorials for those who already know Flutter, Jetpack Compose, SwiftUI or React Native and want the CrossFly equivalent.

The single source of truth for the CrossFly API — the rest of the site links here.

Discover sample apps, tutorials, videos, community, changelog, roadmap and how to contribute.

Short answers to CrossFly's frequently asked questions, each with a link to the canonical page.

Common CrossFly errors and how to resolve them — symptom, cause and fix, grouped by phase.