FlagDeck - World Flags Quiz

FlagDeck is the world flags quiz app that uses science-backed learning to make geography stick.

■ Core Values • All learning data stays on your device — no account, no sign-up • SM-2 spaced repetition algorithm: scientifically proven long-term memory formation • 100% offline: works on planes, subways, anywhere without internet

■ Features

World Flags Quiz 249 ISO 3166-1 official countries in a 4-choice quiz format. Built-in confusable mode for easily mixed-up flags (e.g., Chad vs Romania, New Zealand vs Australia).

SM-2 Spaced Repetition Review Missed flags and aging cards are automatically queued for review. The SM-2 algorithm calculates optimal review timing based on the Ebbinghaus forgetting curve — maximum retention with minimum study time.

Daily Challenge 10 new questions every day, seeded by date so everyone worldwide faces the same set. Compete with friends and track your streak.

Country Flash Cards Beyond flags: capitals, currencies, languages, area, population, region, country code, and driving side — all in one card. Perfect for geography exams, trivia, and general knowledge.

Hear Every Name Pronounced Tap the speaker button to hear any country name or capital spoken in clear, natural English — neural text-to-speech audio bundled right in the app, so it works offline too.

Share Your Score Save quiz results as a shareable card and post to social media. Challenge your friends to beat your flag recognition score.

Fully Offline All data is bundled in the app. Every feature works without Wi-Fi, LTE, or any network connection.

■ Data Sources Country, capital, and currency data: Wikidata (CC0 license). Flag SVGs: flag-icons (MIT license).

■ Privacy Your learning data, including your nickname and study records, stays on your device and is never transmitted externally. To keep the app free, FlagDeck shows ads (Google AdMob) and collects screen-usage statistics (Google Analytics for Firebase) to improve the service. See our Privacy Policy at https://legal.therene.co.kr/flagdeck/

■ Contact support@therene.co.kr

Built by a solo developer who simply wanted to memorize country names and capitals. I hope it helps others with the same goal. Feedback is always welcome.