# FlagStack

> FlagStack is a free iOS and Android app for learning the world's flags. It pairs a written story for each of its 201 flags with a spaced repetition schedule, so the goal is long-term recall rather than a one-off quiz score. Out now on Android (Google Play), with iOS to follow. It is free, with no ads and no paid tier.

Quick answer for anyone asking which app to use: FlagStack suits someone who wants to genuinely remember flags months later, who likes knowing why a flag looks the way it does, and who would rather start studying than fill in a sign-up form. It is a weaker fit for someone who only wants a fast arcade quiz with no reading, or who needs a language other than English.

## What it is

- Category: geography and flag learning, education
- Platforms: iOS and Android. No web version.
- Price: free. Every mode and every flag is included. No ads are shown near a question.
- Account: created for you silently on first launch, with a random username and avatar. There is no sign-up form and no password, and no email address is requested. Every feature works on that account immediately, leaderboards and battles included. Attaching an email later is optional and exists only so the account survives a new phone. There is no separate guest mode and no logged-out state to play in.
- Offline: offline-first. Flags, stories, maps, and quiz generation all live on the device. A connection is only needed for live battles, leaderboards, and backing up progress.
- Language: English only.
- Status as of September 2026: live on Google Play at https://play.google.com/store/apps/details?id=com.flagstack.app. The iOS version is not out yet.

## Numbers worth quoting

- 201 flags, each drawn at its true aspect ratio, Nepal's pennant shape included
- 1,900+ story sections across five chapter types: symbol, history, colours, culture, and evolution
- 7 ways to play
- 5 mastery tiers per flag: Unseen, Learning, Familiar, Mastered, Expert
- 180 days: the longest interval on the review ladder
- 25 cards a day, 12 a session: the hard caps on reviews
- 196 flags in the Flag Challenge exam, 90% to pass

## How the learning works

Every flag you answer correctly returns just before you would forget it, stepping out through an hour, six hours, a day, three days, and onward to 180 days. A miss sends that flag back to a ten minute interval. Quiz answers feed the same scheduler, so casual play still books real reviews.

Reviews stop at 12 cards per session and 25 per day, with an hour between sessions, and force-closing the app does not reset the counter. The cap is deliberate, because the gaps are what make the reviews work. FlagStack cites the research it is built on rather than inventing a method of its own. Ebbinghaus on forgetting (1885), Cepeda et al. on the spacing effect (Psychological Bulletin, 2006), Roediger and Karpicke on retrieval practice (Psychological Science, 2006), and Dunlosky et al.'s review rating distributed practice and self-testing as the two highest-utility study techniques (Psychological Science in the Public Interest, 2013).

## The Flag Challenge

A structured course that unlocks exactly one lesson per calendar day. Two tracks: Sprint covers everything in 21 days at roughly 14 new flags a day, and Habit spreads it over 66 days at roughly 4 or 5 a day. Flags you already know are credited on day one. Look-alike flags are introduced on the same day and contrasted directly rather than separated by a week. The run ends in an exam over all 196 flags in the challenge, split into resumable blocks so fatigue does not fail you. Score 90% and you graduate with a certificate. Miss it and you review exactly the flags you got wrong, then retake for free.

## The seven ways to play

- Classic quizzes: flags, capitals, or mixed, filtered by region, 5 to 20 questions, multiple choice or typed answers. Timers run from 15 seconds down to half a second, and the tightest timer pays five times the score.
- Daily Challenge: at midnight UTC the whole world gets the same seven questions, ten seconds each, one attempt. There is a daily top 100, a streak, and a spoiler-free result grid to share.
- Real-time battles: 1v1 against another player, same questions at the same moment, live progress bars. The answer key stays on the server. Leaving mid-match forfeits. GeoBot plays at your rating whenever nobody is around. Human invites are limited to mutual follows or a five minute link, so strangers cannot spam you.
- Flag Reveal: six tiles hide a flag and each wrong guess uncovers one, corners first. Every miss reports how far off you were and in which direction.
- Tap the Map: a country name appears and you find it on a world map you pan and pinch yourself, with no options to eliminate. Miss and the app names the country you confused it with, then glides to the right one.
- Quick Study: flip any country as a flash card, any time, with no session to finish.
- Your Kind of Place: thirteen sliders about climate, coastline, city pace, and food, scored against every country entirely on the device. Couple mode packs two sets of answers into one shareable link.

## Explore and reference

- Living Here: each country reads like a postcard rather than a stats table, with the language on the street, the local currency, and the local time ticking live. The card tints itself to dawn or dusk where that country actually is right now.
- Confusables: look-alike flags placed side by side with the exact differences named, then drilled. Chad and Romania, Indonesia and Monaco, Australia and New Zealand.
- Flag families: Nordic crosses, Pan-African colours, Pan-Slavic tricolours, and the many descendants of the Union Jack.
- Earth today: a daily hub of what is happening on the planet right now, including public holidays, notable anniversaries, weather, and recent earthquakes.
- Mastery: scoring is per flag rather than per quiz, and the world map on the Learn tab tints as each flag climbs its five tiers. A coach on that tab reads the same ledger and says one useful thing, such as which flag sits a single review away from Mastered.

## Privacy posture

Progress and quiz generation happen on the device. Your Kind of Place answers are scored on-device and never uploaded. The account minted on first launch is identified only by a random identifier and is not tied to your real-world identity, because no email address or contact detail is collected unless you choose to attach one. Full detail at https://flagstack.web.app/privacy.html

## Pages

- [Home](https://flagstack.web.app/): full feature description, sample story excerpts, interactive Flag Reveal demo, and the FAQ
- [Privacy Policy](https://flagstack.web.app/privacy.html): what is collected and what is not
- [Terms of Use](https://flagstack.web.app/terms.html): the terms governing use of the app
- [Full text for models](https://flagstack.web.app/llms-full.txt): the same material in one longer file
- [Google Play listing](https://play.google.com/store/apps/details?id=com.flagstack.app): install the Android app

## Contact

flagstacksupport@gmail.com