Privacy Policy

1. Operator and scope

The data controller for Mighty Key is 제이에스 스튜디오(JS Studio). Privacy enquiries and rights requests: support@mighty-key.js-studio.dev. Business details are available in the business information link below.

This policy covers the iOS and Android apps, keyboard extension, server AI, credits and support. Sign-in is required to enter the app; there is no guest entry. The app does not use an age-confirmation checkbox or collect birth dates or identity documents. Online AI and top-ups are currently available in Korea, the United States and Japan. Installation eligibility follows each store’s content rating and account settings.

2. On-device typing and AI transmission

Basic keystrokes are processed on your device; the keyboard does not send everything you type to a server. Once signed in and set up, basic typing uses no internet or credits. Settings, languages, protected words and consent are stored on-device. Your complete protected-word list is not transmitted.

After separate transmission consent, server AI automatically checks up to 300 readable characters after a 0.7-second pause. For longer text, tap Spelling to check up to 500 characters before the cursor. Translation requires a button request. Guided practice sends step-by-step button requests only. Requests include the target text, protected words appearing in it, source and target languages, request ID, authentication and app version information needed to operate the feature. Text changes only when you apply a suggestion.

Server features in the iOS keyboard require Full Access, separately from AI transmission consent. Withdrawing consent in settings stops subsequent automatic and manual server AI requests. Optional built-in correction on supported devices processes text locally and does not switch to server AI without consent. SDK diagnostics are described separately below.

Detected sensitive password, verification and payment input is blocked on-device, with additional server checks. We cannot identify every secret. Do not submit credentials, financial information or sensitive information about other people for correction or translation.

3. Data and purposes

Account and authentication: Google or Apple sign-in proof, hashed provider account identifiers, app account ID, installation identifiers, sessions and tokens support account creation, persistent sign-in and security. A display name supplied by Google is used for account identification and support and updated at subsequent sign-in. The email address verified by your sign-in provider is stored for account identification and customer support, refreshed at your next sign-in and deleted with your account. If you choose Apple’s Hide My Email, the relay address Apple provides is stored.

AI and usage: target text and results, relevant protected words, languages, model, request timing and status, token usage and charges provide correction and translation, credit accounting and error handling. We do not maintain a per-account sentence history. Response caching and provider retention are described below.

Purchases: product and transaction identifiers, purchase and refund status, country, currency and amount, verification proofs and credit transactions support validation, restoration, refunds and duplicate-grant prevention. Purchase proofs and billing event details are encrypted. We do not collect card numbers or banking passwords; Apple and Google process payment methods.

Diagnostics and security: app and OS versions, device and installation identifiers, feature events, error codes, latency and outcomes support operation and troubleshooting. Text-free diagnostics for designated test accounts may be linked to the account. Cloudflare processes IP addresses and request metadata to deliver HTTPS requests, provide security and check service countries. The app does not request GPS location, contacts or phone permissions.

Support: email addresses, message headers and enquiry contents you send are used to respond and verify account-deletion requests. They are encrypted separately from login data and are not used as AI input or training data.

Product analytics: we link sign-up and sign-in events; server correction and translation requests and displayed results with their feature, source (app or keyboard, inside Mighty Key or another app), outcome and timing; keyboard setup steps (keyboard enabled, ready for AI — iOS Full Access confirmed or Android default keyboard selected), practice completion and applied suggestions with their timing; and verified payment references to app account IDs and platforms to improve acquisition, activation, retention and purchase flows. To measure advertising, we link only the campaign values of the Google Play install referrer (utm_source, utm_medium, utm_campaign, utm_content, utm_term) on Android, and on iOS only the Apple Ads campaign, ad group and keyword IDs that Apple returns for the AdServices attribution token. We do not use or store advertising identifiers (IDFA, advertising ID) or click IDs, and we do not combine this with other companies’ app or website data. Analytics events contain no input text, results, display names, email, IP addresses or authentication tokens. These text-free product events and acquisition records are retained for 90 days, expired records are cleaned up hourly, and linked records are deleted on account deletion.

4. Providers, SDKs and international processing

Cloudflare, Inc. provides server, database and authentication infrastructure, AI Gateway, response caches and support email receipt. Correction and translation are processed by the model the operator selects: OpenAI models through the paid OpenAI API via Cloudflare, or Cloudflare Workers AI models (for example Z.ai’s open GLM-5.3 Flash model) on servers Cloudflare operates itself, in which case text is not sent to the model’s developer. AI target text and processing information are transmitted over HTTPS when requested; protected words are replaced with protection markers before model transmission. Processing may occur outside Korea, including the United States and Cloudflare’s global infrastructure. Korea-only processing is not guaranteed. Declining or withdrawing AI transmission consent prevents use of server AI.

Google LLC and Apple Inc. provide the selected sign-in and store payments. Google sign-in SDKs and Play services may process account information, name and email, device and installation identifiers and usage information for authentication, security and service diagnostics. The iOS Google SDK privacy manifest also declares phone number and approximate location, among other data. This does not mean the app requests phone, GPS or contacts permissions.

Optional Android ML Kit GenAI correction processes text on-device. Its SDK may send device, app and installation identifiers, feature and download events, input and output sizes, configured languages, errors and performance information to Google for diagnostics and usage analytics. Local text processing does not imply that SDK diagnostics are never collected.

These services may process data internationally, including in the United States. Their retention and deletion terms are available in the official links below. We do not sell personal data or use it for targeted advertising or cross-app tracking. Processing needed for AI, authentication and payments is separate from advertising sharing.

5. Retention and deletion

Account, display name, installation and sign-in links, and account credit and usage records are kept during service use and deleted on account deletion. Sessions are revoked and all devices are signed out. Apple authorization revocation and asynchronous cleanup may retry until completed. Revoked-token hashes may remain temporarily to prevent reuse for the session lifetime.

AI text is excluded from ordinary request and response logs. The current policy also prevents new payload logs for designated test accounts and administrator AI tests. Identical AI responses may be cached on Cloudflare for up to one hour; provider prompt caches follow the model’s terms. Hashing a cache key does not anonymize the cached content. Shared response caches are not linked to accounts and expire within one hour independently of account deletion.

Text-free account diagnostics are retained for 7 days, support email for 90 days and billing notification details are available for 90 days; expired notification records are cleaned up when the next notification arrives. Linked billing notifications are also removed when their purchase record is deleted. Unlinked transaction hashes and financial ledger amounts remain for refunds and duplicate-grant prevention and currently have no automatic expiry. Hashing does not guarantee complete anonymization.

Paid OpenAI API inputs and outputs are not used to train models, and optional response storage is disabled. Cloudflare Workers AI does not use inputs or outputs to train models or improve services either. Provider security and abuse-monitoring retention is separate: OpenAI normally retains abuse-monitoring data for up to 30 days, with longer legal or security exceptions. We do not promise Zero Data Retention. Previously created provider logs and Google or Apple SDK data follow each provider’s retention and deletion policy.

6. Your choices and rights

Withdraw AI transmission consent or delete your account in app settings. Deletion also removes remaining credits; check your balance first. Uninstalling or signing out does not delete your server account. If you cannot use the app, follow the account-deletion page below or contact support.

Contact support@mighty-key.js-studio.dev to request access, correction, deletion, restriction or information about international AI transmission. We verify ownership as needed and explain any applicable limits or retention reasons. Do not send passwords or original identity documents unsolicited. Local settings and protected words can be removed using app settings or your operating system’s app-data controls. Current credit purchases do not renew automatically. Any older store subscription must be cancelled separately with the store.

7. Safeguards and updates

We use HTTPS, encryption for purchase and support details, restricted access to credentials and account-deletion procedures. Text is processed within the scope you choose for AI transmission. Changes appear here with an updated effective date; changes requiring new consent are explained separately in the app.