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Privacy

Updated November 2, 2026. This page describes the data processed by Nhẩm Nhanh.

You can play as a guest

No account is required to play. An account keeps your records, NQ and progress across devices.

Data we keep

Purpose and access

Data supports accounts, result verification, recovery, difficulty and engagement analysis, and feedback. Display names and records appear on leaderboards; two opponents can view their head-to-head history. Recovery and contact details do not appear on leaderboards. The game operator can access administrative data.

Vercel serves the website, Railway hosts the server and database, and Resend delivers recovery emails you request. This game has no advertising SDK or tracking across other companies' apps. Infrastructure providers may process technical logs as part of their services.

Recovery phone numbers

You may provide an optional recovery phone number when creating an account. It is not public. Only the game operator can view it to investigate and contact you about account recovery at your request. Recovery phone numbers are stored separately from feedback contact details. Providing a recovery number does not opt you in to feedback invitations. Your email is used for feedback invitations only if you separately agree after creating your account.

Retention and deletion

Account data and history are retained for the features above. There is currently no general automatic deletion period for analytics. In Account → Delete account, enter your password and confirm to delete your account, contacts, records, NQ, progress and linked analytics. Opponents keep match results with your identity removed. Earlier guest data is removed by device only when it is not mixed with another account's history.

Technical backups rotate, retaining up to three automatic server copies. Deleted data may remain in a backup until that copy is replaced. Backups are not shown in the app. Clearing app/browser data only removes local storage, not data already sent to the server.

Your choices and support

You can skip surveys and feedback, play as a guest, change language or delete your account. For data requests or help when you cannot sign in, see Support. Never include your password in feedback.

Tiếng Việt

Apple Pencil and Google ML Kit

Handwriting recognition uses Google ML Kit Digital Ink Recognition. Ink and recognition results are processed on the iPad; ML Kit does not send that input or its recognition output to Google. Numeric answers you submit use the normal Nhẩm Nhanh server flow for scoring and run verification, just like number-pad answers.

ML Kit downloads models, may contact Google for updates, and sends SDK diagnostic and usage metrics: device type, OS/app versions, per-installation identifiers, model languages, download/recognition events, processing latency and error codes. Google uses these metrics to operate, measure and improve the SDK under the ML Kit terms and privacy information. See ML Kit’s iOS data disclosure.

Player safety and direct support

You are free to choose a nickname. Automatic name filtering only blocks clear racial slurs before public display; slang and profanity are not blocked merely for being impolite. You can report or block players from leaderboards, group rooms and head-to-head rooms, and unblock them in Account → Blocked players. Blocks are stored for the current account or device session to hide blocked players and prevent both sides from sharing a room.

Reports contain the relevant player identifier, reported name, reason and details you choose to send. Only the operator can read reports to address abuse; reports do not automatically punish a player. The operator can hide public names or restrict public features. Appeals are available through direct support.

The support form does not require sign-in. It stores the request type, message and any email or username you provide. Email is used only for that support request, not automatically for feedback or advertising. Keep the private request code confidential: it grants access to the reply. Your browser may remember the latest request code on your device for lookup.

Answered support requests and resolved reports are removed by daily maintenance once they have been resolved for 180 days; open requests are kept while they are handled. Blocks remain until unblocked or the related account is deleted. Account deletion removes that account’s support requests and submitted reports, and removes its identifying name from reports submitted by others. Information needed to maintain blocks/restrictions may remain under an identifier no longer linked to the deleted account.

Practice on your device

Question review details and practice progress are stored locally in this browser, separately for guests and each account. Recommendations use evidence from the last 30 days; review history keeps up to 20 recent games. Practice does not send answers or typed content to analytics, and does not award points, NQ or tier unlocks. Clearing browser data removes local progress; account deletion also clears that account’s practice progress on the current device.

Usage analytics and legitimate interests

Nhẩm Nhanh usage analytics is enabled by default to understand play, evaluate difficulty, identify issues and improve the game. We rely on legitimate interests for this purpose where applicable law permits. This basis does not replace a requirement to obtain consent where the law requires it.

Analytics includes random app/browser identifiers, sessions and plays, screens, actions, timing, results, skill statistics, link sources and error signals. It may be linked to your account when you sign in. We use it for internal analysis, not personalised advertising or sale to others.

In the Nhẩm Nhanh app on iPhone, iPad and Android, you can turn this off in Account → Privacy → Usage analytics. Your preference is saved on this device across sign-in and sign-out. A previously saved opt-out remains in effect. Turning it off stops this app version from sending separate analytics events and discards its unsent queue. Previously stored data is not automatically deleted; see Retention and deletion below. Data needed for scoring, saved progress, sync, safety and service operation is still processed. This setting does not control Google ML Kit’s own metrics; see Apple Pencil below.