Privacy Policy

1. Acceptance and Scope

2. Definitions

3. Information We Collect

We collect the following categories of Personal Information:

• Account information: name, email address, hashed password (for email/password users), profile image (optional), preferred language, role, and account creation date.
• Authentication and session information: session token, session expiry, IP address, user agent, and approximate geographic location (city, region, country) derived from your IP address. For Google or Kakao social login, we receive a unique identifier, your profile name, email, and profile image, along with OAuth access and refresh tokens.
• Phone and verification: phone number (when you choose to provide it), one-time verification codes (transient), and verification status.
• Profile and onboarding information: target examination, target score, examination date, motivation for studying English (free-text), prior examination history, country of residence, English proficiency placement (CEFR), and any notes you provide.
• Marketing and attribution: how you arrived at the Service (UTM parameters, referring URL, referral code, tracking link click), recorded once when you first visit and on signup.
• Diagnostic test results: voice recordings of read-aloud and free-speaking sections, transcripts of your spoken responses, the full text of your written essay, your composite and per-skill scores, and the structured JSON output of our AI evaluators.
• Exercise submissions: the full content of your written and spoken practice answers, audio recordings of your speaking practice, AI evaluation output, teacher feedback, and an event log of your interactions with each exercise (timestamps, tab focus changes, item navigation).
• Vocabulary and progress data: spaced-repetition state for each word you study, day and session completion records, weekly progress snapshots, IELTS band estimates, and streak history.
• AI chat: every message you send to and receive from the AI study assistant, including any tool calls and their arguments. Messages flagged by automated moderation as potentially abusive, illegal, or self-harming are stored separately for review.
• Payment information: order ID, payment key, paid amount, payment timestamp, and refund eligibility status. We do NOT collect or store your card number, CVV, expiry, or any cardholder-authentication data; these are handled directly by Toss Payments.
• Communications metadata: a log of every transactional email and Kakao Alimtalk we send you, including the recipient address or phone number, the template used, the variables substituted, the delivery status, and any provider error message. Recipient identifiers and content variables are redacted from this log after 180 days.
• Consent records: a record of each consent you grant (terms, privacy, third-party transfer, marketing), the policy version you consented to, the timestamp, and your IP address and user agent at the moment of consent.
• Anonymous tracking: when you visit a campaign tracking link, we record a session identifier, a SHA-256 hash of your IP address (we never store the raw IP), a truncated user agent, the referrer, and the country derived from your IP. This is later linked to your lead profile if you sign up.
• Customer support correspondence: any messages you send us through email or other channels.

4. How We Collect Information

We collect Personal Information in the following ways:

• Directly from you when you create an account, complete a diagnostic test, complete onboarding, submit an exercise answer, send a message to the AI chat, or contact our support.
• Automatically when you use the Service, including session telemetry, device and browser information, geographic location derived from your IP address, and an event log of your interactions with each exercise.
• From third parties when you sign in with a social provider (Google or Kakao), or when our payment processor (Toss Payments) confirms a payment.
• From cookies and local storage as described in Section 11.

5. Purposes of Processing

We process your Personal Information for the following purposes:

• To create and operate your account and to authenticate you when you sign in.
• To deliver the Service to you, including showing you the curriculum, evaluating your exercise submissions with our AI tools, returning AI feedback and scores, and tracking your progress over time.
• To process payments, issue receipts, and administer refunds.
• To send you transactional communications about your account, payments, exercises, live classes, and progress, by email and by Kakao Alimtalk.
• To provide customer support and to respond to your inquiries.
• To detect, prevent, and respond to fraud, abuse, security incidents, and violations of our Terms of Service, including by automated and manual content moderation of AI chat messages and exercise submissions.
• To comply with our legal obligations, including record-keeping required by Korean tax law, the Act on the Consumer Protection in Electronic Commerce, and the Act on the Establishment and Operation of Private Teaching Institutes (학원의 설립·운영 및 과외교습에 관한 법률).
• To improve the Service, including using de-identified, anonymized, or aggregated data to refine our curriculum, evaluation models, and product design.
• To understand how visitors find us (marketing attribution) and to evaluate the effectiveness of our outreach.
• Where you have given separate consent, to send you marketing communications about new programs, cohorts, or features.
• Where you opt in when you enroll, to allow a member of our coaching team (your advisor) to view your profile, study data, and progress, and to contact you by KakaoTalk, phone, or email to help you stay on track. This is optional, and you can withdraw it at any time in Settings.

6. Legal Bases for Processing

Under PIPA, we rely on the following legal bases:

• Performance of a contract: processing necessary to provide the Service you have signed up for, including delivering exercises, evaluating your work, and processing payments.
• Consent: where you have given specific, informed consent (for example, marketing communications, third-party data transfers, or processing of any sensitive information).
• Legal obligation: where processing is required by Korean law, including tax records, electronic commerce records, and consumer dispute records.
• Legitimate interests of the Company or a third party: where processing is necessary for fraud prevention, security, abuse detection, debt recovery, or the protection of our rights, and your fundamental rights do not override those interests.

7. AI Processing and Automated Decisions

8. Sharing with Third Parties

9. Subprocessors

We engage the following Subprocessors to operate the Service. Each is bound by a written agreement requiring appropriate security measures and limiting their use of your information to the purposes described:

• Toss Payments (South Korea): payment processing, refund processing, payment status webhooks. Receives payment metadata, the buyer's name and phone number for Alimtalk receipts, and order details.
• Solapi (South Korea): Kakao Alimtalk delivery for transactional notifications (purchase confirmation, vocab reminders, weekly reports, phone verification codes, missed-day reminders, streak warnings, cohort start reminders). Receives recipient phone number in national format and template variables. SMS fallback is structurally disabled.
• Resend (United States): transactional email delivery (verification, password reset, weekly reports, lead nurture, missed-days, graduation, cohort announcements). Receives recipient email address, subject, and body content.
• Vercel, Inc. (United States): web application hosting, edge function execution, and Vercel Blob object storage for audio recordings, profile images, and other user uploads.
• Vercel AI Gateway (United States): proxy layer for all AI inference requests. Forwards prompts, audio, and text to the underlying AI providers and returns model output.
• Google LLC (United States): Gemini model family used for speech evaluation and scripted speech evaluation. Receives audio recordings, reference texts, and prompts routed through Vercel AI Gateway.
• Anthropic, PBC (United States): Claude model family used for writing evaluation. Receives writing prompts and the full text of your written submission routed through Vercel AI Gateway.
• DeepSeek (Hangzhou DeepSeek Artificial Intelligence Co., Ltd.) (People's Republic of China): large language model used to power the AI chat assistant. Receives your AI chat messages and related tool-call arguments routed through Vercel AI Gateway. Does not receive your voice recordings or written exercise submissions.
• Neon, Inc. (United States): managed PostgreSQL hosting for our primary database.
• Upstash, Inc. (United States): managed Redis used for rate limiting, idempotency locks, and short-lived caching of authenticated session data.
• Functional Software, Inc. (Sentry) (United States): error tracking and performance monitoring. We strip authorization headers, cookies, and request bodies before transmission, but stack traces and request context are sent. Sentry is operated under our project configuration.
• Axiom (United States): structured log aggregation. Receives log entries that may include user identifiers, request identifiers, IP addresses, and operational metadata. Optional and conditional on environment configuration.
• BunnyWay d.o.o. (Bunny.net) (Slovenia, European Union): video content delivery network used to deliver recorded live classes and curriculum video.
• ElevenLabs Inc. (United States): text-to-speech synthesis used to produce fixed curriculum audio and the fixed examiner prompt audio in the speaking flow. Processes only our scripted prompt text, not learner-submitted content or Personal Information.
• Meta Platforms, Inc. (United States / Ireland): operates the Meta Pixel browser script and the Meta Conversions API, used to attribute conversions (page views, sign-ups, checkout initiations, purchases) for the purpose of measuring our advertising on Facebook and Instagram. Engaged ONLY when you grant marketing consent via our cookie banner. Receives, depending on event: SHA-256-hashed email, SHA-256-hashed internal user identifier, your IP address, your user agent, the event name and ID, the source URL, the timestamp, and (for purchase events) the order value and currency. We do not transmit unhashed email, your name, your phone number, your physical address, or any of your learning content to Meta. Disclosed in detail in our Cookie Policy, Section 7.
• Vercel Web Analytics and Vercel Speed Insights (operated by Vercel, Inc., already listed above): aggregated, anonymized site-usage and performance metrics. Engaged ONLY when you grant marketing consent via our cookie banner. Do not set persistent cookies.
• Google LLC and Kakao Corp. (where you choose social sign-in): identity providers. We receive only the basic profile fields you authorize.

10. International Data Transfers

• Recipients in the United States: Vercel, Vercel AI Gateway, Google LLC (Gemini, OAuth), Anthropic, Neon, Upstash, Sentry, Axiom, Resend, ElevenLabs. Conditional on marketing consent: Meta Platforms, Inc. (United States and Ireland).
• Recipients in the People's Republic of China: DeepSeek (Hangzhou DeepSeek Artificial Intelligence Co., Ltd.), which powers the AI chat assistant and receives your AI chat messages and related tool-call arguments.
• Recipients in the European Union (Slovenia): BunnyWay d.o.o.
• Recipients in the Republic of Korea: Toss Payments, Solapi, Kakao (OAuth).
• Items transferred: as described for each Subprocessor in Section 9.
• Method and timing of transfer: real-time over encrypted connections (HTTPS / TLS), at the moment processing is required to deliver the Service.
• Retention by recipient: each Subprocessor retains the data only for the duration necessary to perform its function, in accordance with its own privacy policy and our written agreement. Audio and writing submissions sent to AI providers are processed at the moment of evaluation and are not retained by the providers for training under our current selections.
• Recipient contact: contact details for each Subprocessor are available on its public website.
• Method and procedure for refusing transfer: you may refuse cross-border transfer by notifying our Privacy Officer (Section 18) in writing or by email, or by deleting your account. Because these transfers are essential to delivering the Service, refusal will prevent us from providing its core functions.

11. Cookies, Local Storage, and Similar Technologies

We use the following client-side technologies. The first set is strictly necessary or required for security; the second set is loaded only when you grant marketing consent via our cookie banner. Our standalone Cookie Policy contains the complete inventory.

• Authentication session cookie (HTTP-only, secure, same-site): identifies your signed-in session. Expires after 7 days of inactivity. You cannot use the Service while signed in without it.
• Consent cookie (`pipa-consent`, 10-minute lifetime): used during signup to remember your consent selections between steps. Discarded once consent is recorded in the database.
• Cookie-banner decision (`tt_consent`, 365 days): records your Accept or Decline decision so we can decide whether to load marketing/analytics scripts.
• Anonymous visitor identifier (`tt_vid`, HTTP-only, 365 days): a random identifier with no personal information, used to link your banner decisions to a server-side audit log entry as required by PIPA Article 22-2.
• Tracking link cookies (`__ttrk`, `tier_session`): set when you click one of our campaign links, used to attribute the source. Lifetime: 30 days.
• Local storage: temporary state for in-progress exercise sessions, exam timers, and captured marketing parameters (UTM, referrer). Cleared when the session ends.
• IndexedDB: temporary storage of in-progress audio recordings during a diagnostic or exercise session, so that a tab refresh does not lose your work. Records older than 24 hours are automatically deleted.

12. Data Retention

We retain your Personal Information only for as long as necessary to fulfill the purposes for which it was collected, to comply with our legal obligations, and to resolve disputes. Specific retention periods include:

• Account information, profile, learning history, exercise submissions, AI chat conversations, voice recordings, written essays, and progress data: retained for the lifetime of your account. When you delete your account, all of this is deleted (see Section 14).
• Authentication sessions and email-verification or password-reset tokens: deleted automatically when they expire (sessions default to 7 days; tokens are typically valid for under one hour).
• Communications log (email and Kakao send records): recipient identifiers and content variables are redacted after 180 days. Operational metadata (channel, template, status, cost) is retained indefinitely for accounting and abuse-prevention purposes.
• Payment records: retained for at least five (5) years from the transaction date as required by Korean tax and electronic commerce law (전자상거래법 시행령 제6조). Refund records are retained for at least three (3) years.
• After you delete your account, transaction records that we are legally required to keep are stored in a separate store, segregated from your other personal information (PIPA Article 21(1) proviso and the Act on the Consumer Protection in Electronic Commerce Article 6(2)). The separately stored items are minimized to the order number, payment key, amount, product name, transaction date, buyer name, and buyer email; they do not include your learning history, voice recordings, written essays, or any other personal data. Once the statutory retention period ends, these records are destroyed without delay.
• Consent records: retained for the lifetime of your account, then for one (1) additional year as evidence of the basis on which we processed your information.
• Audit logs and security event logs: retained for one (1) year for security investigation and abuse-response purposes.
• Anonymous campaign tracking (hashed IP, country, user-agent prefix): retained for one (1) year for marketing analytics, then deleted or aggregated.
• Idempotency locks and cached data in Redis: short-lived (5 minutes to 30 days), used solely to ensure correct behavior of the Service.

13. Security Measures

We take the following measures to protect your Personal Information, in line with PIPA Article 29:

• Transport encryption: all traffic between your device and our infrastructure is protected by TLS.
• Storage encryption: our database (Neon) and object storage (Vercel Blob) encrypt data at rest using provider-managed keys.
• Password storage: passwords are never stored in plain text. We use a strong adaptive password hashing algorithm (managed by Better Auth).
• Session protection: session cookies are HTTP-only, secure, and same-site, preventing access by client-side scripts.
• Rate limiting: aggressive per-user and per-endpoint rate limits on authentication, password reset, AI evaluation, AI chat, and other sensitive operations.
• Access control: role-based access on every server-side endpoint. Production database access is restricted to a small number of authorized engineers.
• Logging and monitoring: structured logging, error tracking, and audit logs for security-sensitive events (signup, login failures, payment status changes, role changes, account deletion).
• Webhook verification: payment and notification webhooks are verified using timing-safe signature comparison and replay-window validation.
• Operational hygiene: stale sessions and expired tokens are cleaned up daily; communications log entries are redacted after 180 days; orphaned profiles are reconciled.

14. Your Rights

Under PIPA Articles 35 through 37 and other applicable laws, you have the following rights regarding your Personal Information:

• Right to be informed: the right to know what Personal Information we hold and how it is processed. This Policy is intended to satisfy that obligation; you may also request a copy of your records by contacting privacy@tieroneenglish.com.
• Right of access: the right to request a copy of the Personal Information we hold about you. You may exercise this right by emailing privacy@tieroneenglish.com from the email address registered to your account; we will respond within ten (10) days.
• Right of correction: you may correct most account and profile information directly in your account settings. For corrections we cannot make through the Service, contact privacy@tieroneenglish.com.
• Right of deletion: you may delete your account at any time from the account settings page. Deletion is irreversible: it removes your profile, exercise submissions, voice recordings, AI chat history, vocabulary progress, and all linked data. We retain certain records (payment records, audit logs, redacted communications metadata) for the periods described in Section 12 to satisfy our legal obligations.
• Right to withdraw consent: where processing is based on your consent, you may withdraw it at any time by contacting privacy@tieroneenglish.com. Withdrawal does not affect the lawfulness of processing performed before the withdrawal.
• Right to object: you may object to processing based on legitimate interests, including marketing communications. We will stop the relevant processing unless we have compelling legitimate grounds that override your interests.
• Right of portability: where technically feasible, you may request that your data be provided to you in a structured, commonly used, machine-readable format. Email privacy@tieroneenglish.com to request a portability export.
• Right not to be subject to a decision based solely on automated processing that produces legal effects or similarly significantly affects you: AI-graded exercise scores are advisory and do not by themselves produce legal effects, but you may request a human review of any AI-graded result by contacting your assigned teacher or by emailing support@tieroneenglish.com.

15. Children's Privacy

16. Sensitive Personal Information

17. Changes to This Policy

18. Data Protection Officer and Contact

19. Remedies and Complaint Mechanisms