Cards.my - Create cards, test your progress and improve your vocabulary

I wanted to share something I’ve been building, Cards.my. It's a vocabulary flashcard app for iOS - I started it in early 2022 and have been chipping at it on weekends since. At its core, it’s still just flashcards: * folders (topic / level / whatever structure you want) * word pairs (your language ↔ foreign language, optional images) * two study modes: * Learn: self-paced, reveal/hide, free navigation, shuffle anytime * Test: shuffled, typed answers, case-insensitive + trimmed input, instant feedback, no backtracking, final score + retry if performance is bad Nothing novel there - that part is intentionally boring. What ended up making it interesting for me were the small «product correctness» details and constraints that stack up over time: - Pronunciation is fully system-based (AVSpeech). The speaker only appears when iOS actually supports a voice for that language, and the app auto-detects the dominant language per folder so you don’t end up with broken audio buttons everywhere. - There’s a cross-folder review mode («Words you often forget») that aggregates weak cards across the entire library based on actual performance history, not just per-deck repetition. - Folders are portable files. You can export a .cardsmy file and send it via AirDrop / Messages / email, and it just imports on the other side. No account needed. - CloudKit handles full sync, including images. Stats are intentionally not «streak-based gamification». Instead: * 7-day practice strip * mastered / weak word lists * revisit queue based on real errors * reminders that adapt to activity instead of nagging for streak preservation There’s also AI-assisted example generation per card: * tap “Examples” → generates a few usage sentences for the target word * strict guardrails (rate limits, quotas, refusal rules) * explicit “AI may be wrong” labeling everywhere it appears On the engineering side, a lot of effort went into boring reliability work: * debounce search everywhere * undo window for folder deletion (5 days) * stable sort persistence * exam hint system * deep links And then the AI layer, which turned out to be more prompt engineering + validation than UI work: * strict JSON schema enforcement * deduping via normalization (case, whitespace, diacritics) * rejection of invalid scopes («10k words», multi-folder requests, etc.) * language-specific grammar rules where needed Tech stack: * 100% native SwiftUI * CloudKit sync * OpenAI for example sentences (with strict quotas + rate limiting to avoid cost blowups) Free tier: 4 folders, 50 cards each. Subscription unlocks everything with a 7-day trial. No ads, no tracking beyond crash + product analytics. If anyone tries it, I’d genuinely appreciate feedback - especially on: * AI sentence quality edge cases * where the study flow feels unintuitive or too «manual» Happy to share a promo code with anyone who wants to try it and give feedback.