Privacy Policy & Terms of Use

1. Overview

Smart Book lets you read books (EPUB, FB2, TXT and our own .sb/.sb2 formats) with inline translation, dictionary look‑ups, word learning, narration and optional cross‑device sync. Much of your data — your library, reading position, saved words and statistics — lives only on your device. Some features send data to our servers or to third parties, and this policy describes exactly which.

2. Who is responsible

Smart Book is developed and operated by Stanislau Kurs, an independent software developer (KursX). The developer is the data controller: they decide the purposes and means of the processing described here and are the party you can contact about your data:

• Stanislau Kurs
• ul. Złota 7 lok. 28, 00‑019 Warszawa, Poland
• Email: apps.kursx@gmail.com

The controller is established in Poland, within the European Union, so Smart Book is directly subject to the GDPR. Because we are established in the EU, we are not required to appoint a separate representative under Article 27 GDPR. Our lead supervisory authority is the Polish Data Protection Authority (Urząd Ochrony Danych Osobowych, UODO); you can also contact the authority in your own country (see section 14).

3. Data we collect

Data you provide

• Account data (optional). You can use Smart Book without an account. If you create one, we collect your email address and a password (stored only as a hash), or — if you sign in with Google or Apple (Apple sign‑in on iOS) — the identity token from that provider, which contains your account identifier, email, name and, for Google, your profile picture and locale. Accounts unlock cross‑device sync and link your purchases.
• Content you create. Books you import, bookmarks, notes and highlights (free text you write), the words and passages you select, your reading progress, learned/known words and per‑book statistics. Most of this stays on your device; some is synced if you opt in (see Sync & backups) or transmitted to translate it (see Translation & AI).
• Your own provider keys (BYOK). If you enter your own translation or AI provider API key and model name, they are stored encrypted on your device and are sent only to the provider you chose — never to us.
• Support & feedback. Messages you send us, including your email address.

Data collected automatically

• Device & installation identifiers (Android). To attribute installs, support multi‑device sync and prevent abuse, the Android app sends our backend a set of identifiers: the Android ID, a device fingerprint, the Google Services Framework ID, the MediaDRM ID, the build fingerprint, your install source/store, app version, timezone, region and locale, and the Google Play install referrer (which may contain a Google Ads click identifier, “gclid”). A device that arrives from an ad campaign is flagged accordingly. The iOS app does not collect these.
• Advertising ID (Android). When ads are shown, the ad SDKs read your device’s Google Advertising ID (see Advertising).
• Push token. A Firebase Cloud Messaging registration token (an APNs token on iOS) so we can send notifications; the device is subscribed to a “book” topic and a topic for your interface language.
• Usage & diagnostics. Analytics events, crash reports and performance traces (see Analytics & diagnostics).

4. Translation, dictionary & AI

Translation is the core of Smart Book, and how your text is handled depends on which mode you use.

Built‑in online translation & dictionary

When you translate a word, phrase or paragraph online, the selected text — together with the surrounding context and a book identifier — is sent to our servers (smart-book.net and its regional mirrors ru., us., nl.smart-book.net), which forward it to the chosen third‑party engine and return the result. Providers include Google, Yandex, Microsoft, DeepL, Reverso, Lingvanex, Papago, Lara and Oxford for translation and dictionary look‑ups, and — for AI translations that use our own keys — OpenAI, Anthropic (Claude), Google Gemini and DeepSeek (with OpenRouter as a fallback). To make translation faster and cheaper, results are cached on our servers. Some word look‑ups (Google, Reverso) are fetched directly from your device to the provider and the parsed result is also added to our shared cache.

Your‑own‑key (BYOK) AI translation

If you supply your own AI provider key, the text — with its context and, for custom prompts, the book title and author — is sent directly from your device to the provider you selected (for example Anthropic, OpenAI, Google Gemini, DeepSeek, OpenRouter, HuggingFace, Perplexity, Chutes, DeepL, or a custom endpoint you configure). It does not pass through our servers, and these results are cached only in the app’s local database.

5. Text‑to‑speech (narration)

The reader narrates books using your device’s built‑in text‑to‑speech engine (the Android system TTS or Apple’s speech synthesizer). In that mode, the text is processed on your device by the engine you selected.

AI voices are provided through a separate, optional “Smart Book synthesizer” app that you install and select as the narration engine. If you choose an AI voice such as ElevenLabs, the text to be spoken is sent through our server to ElevenLabs to generate the audio.

6. Analytics, crash reporting & performance

Smart Book uses Google Firebase to understand how the app is used and to keep it stable:

• Firebase Analytics — named events such as opening a screen, creating a book, adding a note, adding an API key, or seeing a trial offer, plus user properties such as your language pair, install store, and subscription/premium status.
• Firebase Crashlytics — crash and error reports, including stack traces, the device/OS state and diagnostic breadcrumbs the app attaches.
• Firebase Performance Monitoring — automatic app‑start, screen‑render and network‑request timings.

The app does not use classic web Google Analytics, and analytics events are disabled in debug builds.

7. Advertising (Android only)

The free Android app may show ads. Ads are served through Unity LevelPlay / IronSource, with Yandex Ads as a fallback (outside Ukraine); mediation may involve Google AdMob, Meta Audience Network, Pangle (ByteDance), Mintegral, Unity Ads and myTarget (VK). These SDKs may read your Google Advertising ID and collect device and ad‑interaction data (impressions, clicks, rewards).

8. Purchases & subscriptions

Purchases and subscriptions are processed by the platform store — Google Play Billing on Android, Apple on iOS — or, for users in Russia, by YooKassa. We receive and store purchase and receipt data (purchase/transaction tokens, order and product identifiers, timestamps and subscription status) and verify it server‑side with Google and Apple. We never receive or store your full card number; card details are handled by the store or payment provider.

9. Cross‑device sync & backups

If you are signed in with an eligible (premium) account, you can sync your reading data across devices. In that case we store on our servers, tied to your account:

• your book‑library metadata, and book‑file backups (stored as ZIP files under your numeric account identifier on storage.smart-book.net);
• your bookmarks and reading position;
• your notes and highlights, including the free text you write; and
• your reading‑time statistics.

Reading‑time totals may appear on a leaderboard that shows your display name (from your Google/Apple profile or email) and ranking to other users. Your learned/known words and per‑book statistics stay only on your device; you can export them locally to Anki or to the separate SmartDictionary companion app, but they are not uploaded to our servers.

10. The website (smart-book.net)

For each visit to our website we record the page path, your browser language, the referring page, any campaign parameters (UTM), and your user agent, and we derive an approximate country‑level location using a local, offline geolocation database (no more precise than the country). We also record outbound clicks and downloads. This is our own first‑party analytics, stored in our database; the public pages use no third‑party analytics or advertising pixels.

The site sets first‑party cookies only, and none from third parties: sb_geo_seen remembers that you dismissed the “switch to your regional site” banner; sb_utm keeps the campaign parameters (UTM) of the link you arrived through for 30 days, so that a download stays credited to the campaign that brought you here; signing in adds the cookies that keep you signed in; and one further cookie is used only for the operator’s admin dashboard. The demo video loads from YouTube only after you click play — at which point Google may receive your IP address and any YouTube cookies.

11. Who we share data with

We share data with the following categories of processors, only as needed to provide the features above. Each acts under its own privacy policy.

We do not sell your personal data. We may disclose data if required by law or to protect the rights, safety and integrity of Smart Book and its users.

12. International data transfers

Smart Book operates internationally and our processors are located in several countries. Depending on the features you use, your data may be processed in the United States (for example Google/Firebase, OpenAI, Anthropic and ElevenLabs), in Russia (for example Yandex, myTarget/VK and our ru.smart-book.net host), in China (Pangle and Mintegral), and on our servers in other regions.

When we transfer personal data of EU/EEA, UK or Swiss users to a country outside their region, we rely on one of the safeguards required by Chapter V of the GDPR:

• Adequacy decisions. Where the destination country (or a certification such as the EU–US Data Privacy Framework) has been recognized by the European Commission as providing an adequate level of protection, the transfer relies on that decision.
• Standard Contractual Clauses. For our processors in countries without an adequacy decision (for example the United States), transfers are made under the European Commission’s Standard Contractual Clauses incorporated into those providers’ data‑processing agreements, together with supplementary measures where appropriate.
• Your request / consent (Article 49). Some features send data to an engine you actively choose — including translation and AI providers, and providers located in Russia or China. Where no adequacy decision or Standard Contractual Clauses apply, that transfer is made because it is necessary to perform the specific service you asked for, or with your explicit consent. You can avoid these transfers by not using the feature (for example by using offline translation).

You can ask us for more information about the safeguards that apply to a particular transfer using the contact details in section 2.

13. Data retention

Data on your device remains until you delete it in the app or uninstall Smart Book. Data on our servers — account details, synced content and backups, purchase records, the translation cache and website analytics — is kept for as long as needed to provide the service and to meet legal and security obligations; the translation cache and analytics records may be retained on a long‑term basis. Data held by third‑party processors is retained under their own policies. When you delete your account we remove your account and sign‑in records (see below).

14. Your rights & choices

Subject to applicable law, and in particular if you are in the EU/EEA, the UK or Switzerland, you have the following rights over your personal data:

• Access — obtain confirmation of whether we process your data and a copy of it.
• Rectification — have inaccurate or incomplete data corrected.
• Erasure — have your data deleted (“right to be forgotten”).
• Restriction — limit how we process your data in certain cases.
• Objection — object to processing based on our legitimate interests, and object at any time to processing for direct‑marketing or advertising purposes.
• Portability — receive the data you provided in a structured, commonly used, machine‑readable format, and have it transmitted to another controller where technically feasible.
• Withdraw consent — where processing is based on consent, withdraw it at any time, without affecting processing already carried out.
• Complaint — lodge a complaint with a supervisory authority (see below).

You also have practical controls in the app and on your device:

• Reset or limit your advertising ID, and opt out of personalized ads, in your device settings (Android).
• Turn off notifications in your device or app settings.
• Use offline translation to keep your text on the device.
• Don’t sign in, to keep your library and reading data local only.

To exercise any right, contact us at apps.kursx@gmail.com. We respond free of charge and normally within one month; we may ask you to verify your identity first. If you are in the EU/EEA you may lodge a complaint with the data‑protection authority of your country of residence, work or the alleged infringement; in the UK, with the Information Commissioner’s Office (ICO); in Switzerland, with the Federal Data Protection and Information Commissioner (FDPIC).

15. Deleting your data

You can delete your account yourself at smart-book.net/user/delete: enter your email and confirm via the link we send you. This removes your account and your Google/Apple/email sign‑in records. To also have your synced content and book backups removed, or if you need help, email apps.kursx@gmail.com and we will action your request.

16. Children

Smart Book is not directed at children under 13 (or the higher minimum age required in your country, such as 16 in parts of the EEA). We do not knowingly collect personal data from children below that age. If you believe a child has provided us data, contact us and we will delete it.

17. Security

We use HTTPS for data in transit, store your own provider keys in the app’s encrypted storage, and verify purchases server‑side. No method of transmission or storage is completely secure, so we cannot guarantee absolute security, but we work to protect your data against unauthorized access.

18. Changes to this policy

We may update this policy as the app evolves. The “last updated” date at the top reflects the current version, and material changes will be reflected here. Continued use of Smart Book after an update means you accept the revised policy.

19. Contact

Questions about this policy or your data? Email apps.kursx@gmail.com.

20. Legal bases for processing (EEA / UK users)

If you are in the EU/EEA or the UK, we process your personal data only where we have a legal basis to do so under Article 6 of the GDPR. The basis depends on the purpose:

Where processing relies on consent, you can withdraw it at any time; where it relies on our legitimate interests, you can object (see section 14).

21. Automated decision‑making & profiling

We do not make decisions that produce legal or similarly significant effects about you based solely on automated processing (Article 22 GDPR). We do use automated processing for limited, low‑impact purposes — for example flagging a device that arrived from an ad campaign, selecting which ads to show (Android), and detecting abuse — but these do not have a legal or similarly significant effect on you.

Terms of Use

You may cancel your subscription and request a refund, without penalty or obligation. Refunds are handled by Google and Apple (or YooKassa for purchases made through it), not by Smart Book.

1. Definitions used in the agreement

1.1. This User Agreement is a public offer. Actual use of the Smart Book application by the User is considered acceptance of the terms of this Agreement.
1.2. The User is a person who has accepted this Agreement by using the Smart Book application.
1.3. The Licensor is the owner of the exclusive rights to the Smart Book application.

2. Status of the agreement

2.1. This Agreement is developed by the Licensor and sets out the terms of use of the Smart Book application and the rights and obligations of the Users and the Licensor.
2.2. This Agreement is binding on the User and the Licensor. Its subject matter is the provision to the User of access to the Smart Book application and its functions. All documents governing access to the application’s functions are an integral part of this Agreement.
2.3. The User should read this Agreement upon installing the Smart Book application. Installing the application means the User’s complete and unconditional acceptance of this Agreement.
2.4. This Agreement may be amended and/or supplemented by the Licensor without special notice. It is a public, generally accessible document, and the Licensor recommends that Users regularly review it. Continued use of the application after changes take effect constitutes acceptance of those changes.

3. User

3.1. The Smart Book application does not require an account for basic reading and translation, and installation is free of charge. Creating an account (via Google, Apple or email) is optional and enables cross‑device sync and linking of purchases.
3.2. The User is an individual who has installed the Smart Book application.
3.3. By installing the application, the User agrees to this Agreement and undertakes the rights and obligations set out in it.
3.4. When using the application, the User shall not:

• use the application in any way other than through the interface provided by the Licensor, except where expressly authorized in a separate agreement with the Licensor;
• reproduce, duplicate, copy, sell, trade or resell access to the application for any purpose, except where expressly authorized in a separate agreement with the Licensor.

4. Licensor

4.1. In this Agreement, the Licensor of the Smart Book application means Stanislau Kurs, an independent software developer, ul. Złota 7 lok. 28, 00‑019 Warszawa, Poland. Email: apps.kursx@gmail.com.
4.2. Any inquiries, proposals and claims addressed to the Licensor in connection with this Agreement and the functioning of the application, or the alleged infringement of third‑party rights, shall be sent to the email address in clause 4.1.
4.3. The Licensor shall comply with applicable law, this Agreement and other documents developed by the Licensor to regulate access to the application’s functions.
4.4. Nothing in this Agreement entitles the User to use the trade name, trademarks, domain names or other identifiers of the Licensor. Any such right may be granted only in a written agreement with the Licensor.
4.5. The Licensor shall be entitled to:

• at any time, at its own discretion, change the design, content and structure of the application, and change or supplement the scripts, software and other objects used;
• suspend, limit or withdraw a User’s access to all or any part of the application, with or without prior notice;
• at its own discretion and without prior notice, change, improve, limit, suspend or terminate the operation of the application and any of its parts and materials.

4.6. The Licensor shall use its best efforts and reserves the right to exclude from the application any negligent, inaccurate, offensive, incorrect or intentionally incomplete information.
4.7. In no event shall the Licensor be liable to Users or third parties for any direct, indirect or incidental damage, including loss of profit or data, or reputational harm, arising from use of the application or from unauthorized placement by Users of third‑party intellectual property in the application.

5. Intellectual property rights

5.1. The Smart Book application is the intellectual property of the Licensor and is protected by applicable intellectual‑property law and international treaties. All rights are reserved.
5.2. No content may be copied, reprocessed, distributed, published, downloaded, transferred, sold or otherwise used in whole or in part without the prior permission of the copyright holder, except where the copyright holder has expressly permitted free use.
5.3. Any use of the application or its content other than as authorized in this Agreement or expressly permitted by the copyright holder is prohibited without the prior written permission of the copyright holder.
5.4. Unless expressly stated in this Agreement, nothing here shall be construed as a transfer of exclusive rights to the content.

6. Subscriptions and application functionality

6.1. Users subscribe to Smart Book services and manage their subscription settings through the App Store and/or Google Play (or, where applicable, the payment provider used at purchase).
6.2. To manage a subscription, the User should follow the official Apple/Google instructions at support.apple.com/HT202039 and support.google.com/googleplay, respectively.
6.3. The application does not provide automated censorship or control of Users’ activities, except for technical measures the Licensor may implement to prevent infringement of third‑party intellectual‑property rights.
6.4. The Licensor may change the design, content and functions of the application at any time, with or without prior notice.
6.5. The Licensor may use aggregated statistical information about the application’s use for the purposes described in the Privacy Policy above, including improving the service.

7. Final provisions

7.1. This Agreement constitutes the entire agreement between the User and the Licensor regarding use of the Smart Book application and supersedes any previous agreements between them.
7.2. This Agreement is governed by applicable law. Matters not regulated by this Agreement shall be governed by the law applicable at the Licensor’s place of residence.
7.3. By accepting this Agreement (clause 2.3), the User consents to the processing of their personal data as described in the Privacy Policy above.
7.4. By accepting this Agreement (clause 2.3), the User confirms that they have read and understood the fees set by the Licensor for use of the application.
7.5. The Licensor does not guarantee any particular results from use of the application.
7.6. In no event shall the Licensor or its representatives be liable to the User or any third party for any indirect, consequential or incidental damage, including loss of profit or data or reputational harm, arising from use of the application or its content, even if the Licensor was advised of the possibility of such damage.
7.7. In case of any dispute related to this Agreement, the User and the Licensor shall use their best efforts to settle it by negotiation; failing that, the dispute shall be resolved in accordance with applicable law.
7.8. This Agreement takes effect for the User upon acceptance and remains in force for an unlimited period.
7.9. This Agreement, together with the Privacy Policy above and any terms you agree to when buying additional features, contains the entire agreement between you and Smart Book regarding use of the service.