Tools
Know what's in the toolbox
What each tool is, how it's licensed, and when a dev would actually reach for it.
Languages & runtimes
Programming languages and the runtimes that execute application code.
Swift
Open sourceNative application programming language
A compiled language used for Apple-platform applications and other native software. Pair it with SwiftUI or UIKit for iOS interfaces and call platform SDKs directly.
Kotlin
Open sourceTyped application programming language
A language with Java interoperability and coroutine support, used for native Android apps and other application targets. Pair it with Jetpack Compose for Android UI.
TypeScript
Open sourceTyped superset of JavaScript
Adds static types and interfaces to JavaScript, then compiles away to plain JS. The payoff is editor autocomplete, safer refactors, and a whole class of runtime bugs caught before you ship.
Rust
Open sourceMemory-safe systems language
A compiled systems language that guarantees memory safety at compile time without a garbage collector. Fast and predictable, at the cost of a steeper learning curve than most web languages.
Node.js
Open sourceJavaScript runtime
A JavaScript runtime built on V8, with Node APIs for servers, files, networking, and processes. Supported releases can execute erasable TypeScript through type stripping; application builds and type checking remain separate decisions.
Bun
Open sourceAll-in-one JavaScript runtime
A JavaScript runtime with an integrated package manager, bundler, and test runner. It transpiles TypeScript and JSX while executing them, and implements many Node APIs so existing packages can work with it.
Python
Open sourceInterpreted general-purpose language
A readable, batteries-included language that dominates data work and machine learning. On the web it shows up as API backends (FastAPI, Django) and anywhere ML models need serving.
C# / .NET
Open sourceCompiled object-oriented platform
Microsoft's cross-platform runtime and C# language, open source and running on Windows, macOS, and Linux. Strong for large backends, desktop apps, and games through Unity.