# DocuChan

> DocuChan is a privacy-first web application for encrypted file exchange, direct device-to-device transfer, peer-to-peer document collaboration, and browser-only PDF processing.

## Browser-only PDF tools

- [Private PDF tools](https://docuchan.bekito.co.jp/tools): Hub for local PDF organization, compression, and privacy inspection. Files selected here are processed in the browser and are not uploaded for processing.
- [Edit and organize PDF](https://docuchan.bekito.co.jp/tools/pdf): Merge PDFs, reorder, rotate, duplicate, delete, add blank pages, and extract selected pages locally. The workspace also checks supported privacy findings before export and lets the user review or remove metadata.
- [Compress PDF](https://docuchan.bekito.co.jp/tools/compress-pdf): Use lossless or raster compression, set an optional target size, and preview the exact output size locally before saving. Privacy choices are applied before the exact compression preview is generated.
- [PDF Privacy Check](https://docuchan.bekito.co.jp/tools/privacy-check): Inspect supported metadata, XMP, annotations, attachments, actions, forms, signatures, and optional layers; edit metadata or create a sanitized copy locally.

## File exchange

- [Send securely](https://docuchan.bekito.co.jp/send): Encrypt files in the browser, then upload ciphertext directly to object storage and create an expiring or burn-after-download link.
- [Beam](https://docuchan.bekito.co.jp/beam): Send a file directly between browsers over WebRTC after verifying a short authentication code.
- [Clipboard](https://docuchan.bekito.co.jp/clipboard): Share text or an image directly between devices.

## Peer-to-peer document collaboration

- [Rooms](https://docuchan.bekito.co.jp/rooms): Create or join a private real-time document room. Rich text, Markdown, locally rendered Mermaid diagrams, comments, selections, embedded images, and collaborator presence synchronize over encrypted browser-to-browser WebRTC data channels.
- Room secrets stay in URL fragments and are scrubbed from the address bar before the application hydrates. DocuChan's server brokers short-lived presence and WebRTC signaling; it does not receive or store document contents, comments, selections, embedded images, or room encryption keys.
- Browser-local recovery is optional and stores the room key plus local Yjs document data on that device. The user can delete individual rooms or all local recovery data. There is no DocuChan server backup and a lost room key cannot be recovered.
- A complete invite link carries the document decryption capability. Unlocked rooms admit a join request immediately; a locked room requires approval from an online host before signaling and document synchronization begin. The separate creator-only host capability stays in browser site storage, never appears in invite/resume URLs, and cannot be recovered by DocuChan. Collaborator display names are self-asserted rather than verified identities, and participants can copy or export content they can see. Rooms prefers direct WebRTC and can use short-lived TURN credentials to relay application-encrypted packets when restrictive networks block a direct path.

## Trust and documentation

- [Security model](https://docuchan.bekito.co.jp/security): Technical explanation of browser encryption, encrypted chunk framing, link keys, Beam authentication, and explicit limits.
- [How DocuChan works](https://docuchan.bekito.co.jp/how-it-works): Product-level explanation of the send and receive flow.
- [Privacy policy](https://docuchan.bekito.co.jp/privacy): What DocuChan processes and what it does not collect.
- [Full LLM reference](https://docuchan.bekito.co.jp/llms-full.txt): Detailed factual boundaries for the product and PDF tools.
- [Agent resource index](https://docuchan.bekito.co.jp/agent-resources): Human-readable index of canonical documentation and machine-readable facts.
- [Product facts JSON](https://docuchan.bekito.co.jp/product.json): Public, read-only product facts. It is documentation, not an upload or automation API.


## 日本向けエディション / Japan-localized edition

- 製品名は DocuChan（ドキュちゃん）です。日本向けエディションは Powered by Bekito と表示し、DocuChan core by Masterbek として開発元を明記します。
- [業務ファイル共有ガイド / Business file sharing guide](https://docuchan.bekito.co.jp/business-sharing-guide?lang=ja): 送信者・受信者向けに、完全なリンク、パスワード、有効期限、保存場所の制約を日本語と英語で説明します。
- [Agent resources / AI・エージェント向け情報](https://docuchan.bekito.co.jp/agent-resources?lang=ja): 人と検索システムが確認できる公式リソース一覧です。
- [Machine-readable product facts](https://docuchan.bekito.co.jp/product.json): 公開情報だけを含む読み取り専用 JSON です。ユーザーファイルや非公開リンクは含みません。
- 日本国内でのデータ保管、認証取得、法令適合、サービスレベルを保証するものではありません。Bekito版では現在、決済機能を提供していません。

DocuChan's interface supports English, Japanese, Russian, Uzbek, and Spanish. Public pages may select a language from the request or the user's saved language preference.