Mobile Development

androidx6.0k★

AndroidX is the foundation under almost everything you build on Android. AndroidX is Google's official library collection for Android development. It provides backwards-compatible versions of Android platform APIs so your app works on older devices without you writing compatibility code yourself. It's the standard library that Android should have shipped with. This repo is the development source for Jetpack libraries: RecyclerView, Room (database), Navigation, Compose (UI toolkit), WorkManager (background tasks), CameraX, and dozens more. If you've used any modern Android API, it probably came from here. Apache 2.0. The star count is low because most Android developers consume these as Gradle dependencies; they don't star the monorepo. The actual usage is in the millions of apps. Everything is free. Google maintains this as part of the Android platform. No paid tier, no premium features, no enterprise edition. The catch: this is a monorepo, not a standalone tool. You don't clone this unless you're contributing to Android itself. As a developer, you pull individual libraries via Gradle. And Google's deprecation cycle is aggressive; APIs get marked deprecated fast, and migration guides aren't always clear.

CodenameOne1.8k★

Codename One compiles Java or Kotlin into native mobile binaries for iOS and Android from a single codebase, without learning Swift or platform-specific languages. Not a webview wrapper. Actual native compilation. Write once in Java/Kotlin, build to iOS (via ParparVM or iKVM), Android (native), web (via JavaScript transpilation), and desktop. The UI toolkit is custom, not native widgets, but rendered to look native. Includes a visual designer, simulator, and build cloud. The free tier lets you build and test locally. The build cloud, which compiles your iOS builds without needing a Mac, starts at $19/month (Basic). Professional is $99/month with additional features. Enterprise pricing available. Solo developers learning Java who want mobile: the free tier gets you started, but you'll need the $19/month plan for iOS builds unless you have a Mac with Xcode. Small teams: $99/month Professional for the full toolchain. Larger teams: evaluate against Flutter or React Native first. The catch: the community is small for a cross-platform framework. StackOverflow answers are sparse, and if the company behind it stops, you're stuck with a niche framework and no ecosystem. Flutter and React Native have massive communities. Codename One's Java angle is its differentiator, but it's also its limitation. The mobile world moved to Dart and JavaScript/TypeScript.

Fabulous1.3k★

Fabulous lets you build cross-platform mobile apps using F# with a functional programming approach. If you're an F# developer (or want to be) and need to ship iOS and Android apps, this is your path. It sits on top of .NET MAUI and gives you a declarative, Elm-style architecture. The pitch: instead of the imperative, state-mutating approach of most mobile frameworks, you describe your UI as a function of your state. State changes, UI re-renders. If you've used React or Elm, the mental model is the same. Small community but dedicated. F# is a niche language and Fabulous serves that niche well. Completely free under Apache-2.0. No paid tier, no cloud service. You need a .NET development environment and the platform SDKs (Xcode for iOS, Android SDK). The catch: F# is niche. Finding F# mobile developers is hard. The ecosystem is small. Fewer libraries, fewer Stack Overflow answers, fewer tutorials compared to React Native, Flutter, or even Kotlin Multiplatform. If you're not already committed to F# and .NET, there's little reason to choose this over more popular options. But if you ARE an F# shop, this is the only real option and it's good at what it does.

app-store-preflight-skills1.2k★

This skill scans your project for common App Store rejection patterns before you submit. It's a pre-flight checklist that catches the stuff Apple will flag so you don't waste a week waiting for a rejection email. It checks for missing privacy descriptions, incorrect entitlements, deprecated API usage, and dozens of other patterns that trip up developers. You run it as a Claude Code skill. Point it at your Xcode project and it tells you what's going to get flagged, still early . MIT licensed, completely free. The catch: Apple's review guidelines change constantly, and this is a community-maintained skill, not an Apple product. It catches the known patterns, but Apple can always find new reasons to reject you. And it's a static analysis. It can't test runtime behavior or UI guidelines that require human judgment.

serve-sim1.1k★

serve-sim streams an iOS Simulator to a browser. You get the framebuffer, gestures, keyboard input, and logs over the network or piped to AI coding tools like Cursor or Claude Desktop. Built by Evan Bacon (Expo). Apache-2.0. Run npx serve-sim and you have a preview server on localhost:3200. Multiple booted simulators work in parallel, daemon mode runs it in the background, and there is middleware for embedding it inside your existing dev server. Solo: easy way to share what you are building with a teammate over Tailscale. Small teams testing iOS apps: stream the simulator to AI agents for visual feedback during development. Teams building infra: this is the foundation if you want to host simulators centrally instead of tying every test session to one engineer's laptop. The catch is macOS. Apple's simulator only runs on Apple hardware, so this serves what you have, it does not conjure a simulator on Linux.

baguette929★

Baguette is a Swift CLI that spins up iOS Simulator devices, streams their screens at 60fps, and injects taps, swipes, and multi-finger gestures without booting the Simulator GUI. Run it on your Mac and you get a headless device farm and an automation harness in one tool. Apache 2.0, requires macOS 15+ and Xcode 26. The hard parts (host-HID input, accessibility tree extraction, frame streaming over MJPEG or H.264) are handled through SimulatorKit and the private accessibility framework, no dylib injection or DYLD_INSERT_LIBRARIES hacks. A web UI runs on localhost:8421 with per-simulator streams and a multi-device farm view. The CLI exposes everything for CI use. Solo iOS developers: free, fast, and the gesture API is more useful than waiting for Simulator.app to boot. Small teams running iOS CI: a real device farm replacement that skips Linux-hosted runners or a third-party cloud. Mid-sized to large teams: useful for screenshot generation, regression sweeps, and integration testing across many simulator configurations. Cloud device farms still win on real hardware coverage. The catch: it relies on private Apple frameworks and Xcode 26 internals. Apple changes those across major releases, so expect breakage when Xcode 27 ships.