A Quick Word on the Others

You'll run into these, and sometimes one is exactly right:

It helps to picture where each language tends to live. Software has layers — what runs in the browser (frontend), what runs on a server (backend), what runs on a phone (mobile) — and most languages have a home turf:

        ┌──────────────────── WHERE CODE RUNS ────────────────────┐
        │                                                          │
   FRONTEND               BACKEND                MOBILE            │
   (browser)              (server)               (phone)           │
        │                    │                      │              │
   ┌────┴────┐        ┌──────┴──────┐         ┌─────┴─────┐        │
   │ JS / TS │        │ JS / TS     │         │ Swift     │ iOS    │
   │ (the    │        │ Python      │         │ Kotlin    │ Android│
   │  only   │        │ Go          │         │ JS / TS   │ (React │
   │  real   │        │ Rust        │         │           │ Native)│
   │ option) │        │ Java / C#   │         └───────────┘        │
   └─────────┘        │ PHP / Ruby  │                              │
                      └──────┬──────┘                              │
                             │                                     │
                        ┌────┴────┐                                │
                        │   SQL   │  ◀── the database, talked to    │
                        │(database)│      from any backend above    │
                        └─────────┘                                │
        └──────────────────────────────────────────────────────────┘

• Java / C#: the workhorses of large enterprises. Mature, stable, heavily tooled, and ideal for big corporate backends and Android (Java/Kotlin) or Windows/.NET ecosystems (C#). AI handles both well. As a solo vibe coder you rarely need them unless you're working within an existing enterprise stack or building for Android/Windows specifically.
• Swift / Kotlin: the native languages for iOS (Swift) and Android (Kotlin) apps. If you're shipping a real mobile app to the App Store or Play Store, you'll likely touch these. AI support is solid but weaker than for web languages, and mobile development carries extra friction (devices, app store rules, build tooling).
• PHP / Ruby: the old guard of the web, and still quietly running a huge slice of it. PHP powers WordPress and therefore a large fraction of all websites; Ruby on Rails remains a fast, opinionated way to build a database-backed app. Both have plenty of training data, so AI handles them well — but they're rarely the first thing a newcomer reaches for today, and you'd typically pick them because you're working in an existing codebase rather than starting fresh.
• SQL (Structured Query Language): not a general-purpose language, but you'll meet it the moment your app stores data. Think of it as the language you use to ask a database questions — "give me every user who signed up this week." SQL queries databases. You don't choose SQL instead of the others — it lives alongside whatever you pick. The good news: AI is excellent at writing SQL, so you can describe what data you want in plain words and let it produce the query.