Frequently Asked Questions

Companion Reader is prioritizing the iOS overseas launch. The web version will open after it is stable; Android, Windows and macOS remain in testing or planning.

Go to the "Download" page for platform status. This site does not offer external iOS membership purchase or unfinished installation packages.

The Android version is still being prepared. Before official release, do not install packages forwarded by others or from unknown sources.

The desktop version is still planned and not open for purchase. Current work prioritizes iOS launch, subscription flow and the core reading experience.

The iOS app is planned to launch first in selected overseas App Store regions. Mainland China availability will be evaluated later based on filing, privacy, content and AI compliance progress.

Yes. The overseas launch needs at least English UI, App Store metadata, privacy policy and support information; Chinese can remain as an optional language.

Yes. Reading, underlining, highlighting, notes and quotes don't need an AI Key. The Key only affects AI chat, summaries, extraction and categorization.

No. Uploaded books are only for your own reading, parsing, sync and AI processing — never public, sold or misused.

EPUB is the primary format. More formats will be added based on user demand.

During preparation, AI usage will prioritize clarity and control. If users bring their own API Key, cost and quota are determined by the AI provider; if system API is offered later, it will be clearly labeled in the app.

Yes. The Key covers AI cost only. Membership controls upload limits, AI permissions, sync and export within Companion Reader.

Not always. AI may err — users can refresh, manually edit, or use future correction features. We never claim AI results are always accurate.

We protect Keys via HTTPS, encryption, masking, log sanitization and deletion. You should also set budget limits with your AI provider and reset if suspicious.

The free version keeps basic reading, bookshelf, underlines, highlights, notes and quotes. Exact limits are shown in the app.

Members get higher product limits, AI permissions, sync and export capabilities. iOS subscription, renewal and restore purchase will be handled through Apple App Store in-app purchase.

If users configure their own API Key, membership does not include third-party AI provider charges. If system API is offered later, fair usage rules will be shown in the app.

No. iOS digital membership will be provided through Apple App Store in-app purchase. This site only provides product information, policy pages and support links.

Yes. You can delete books, notes, API Keys and your account. Data is removed or anonymized within a reasonable period, except where law requires otherwise.

If the product offers history and sync, AI chats may be saved. Users can view and delete them in-app, per privacy policy and settings.