★★★★★ OSS
Self-hosted file sync, sharing, and collaboration. Pair with Collabora or OnlyOffice to build a Google Workspace–like stack.
- 完全データ主権
- Collabora/OnlyOffice連携
- Cal/Contacts/Talk
- エコシステム巨大
⚠ サーバー運用必要
なぜ Google Drive / Docs から離れる？
When contracts, drafts, and personal notes live on one platform, account suspension or AI policy shifts hit everything at once. Encrypted storage, self-hosting, or E2EE SaaS restores confidentiality and portability.
Googleの限界・リスク
- • Free 15 GB is shared with Gmail and Photos
- • Docs/Sheets center on Google formats—offline and interoperability have limits
- • Gemini and other AI features assume access to Drive content; opt-out is getting harder
- • Shared link permission mistakes cause frequent leaks
- • Data location and legal requests follow Google’s cloud policy
- • Detailed audit logs and compliance certs are limited outside Workspace
選び方ガイド
全部試す必要はありません。あなたの優先順位に合わせて絞り込みましょう。
- 1 Full sovereignty on-prem: Nextcloud + Collabora or OnlyOffice
- 2 Easy E2EE cloud: Proton Drive or Sync.com
- 3 Browser-only E2EE co-editing: CryptPad
- 4 Enterprise compliance E2EE: Tresorit
- 5 Large capacity encrypted cloud: pCloud or Sync.com
- 6 Microsoft-compatible office alone: OnlyOffice Document Server or Collabora Online
クイック比較
プライバシー・使いやすさ・機能・コスパの4軸で評価しています。
| ツール | Privacy | Ease of use | Features | Value | 総合 |
|---|---|---|---|---|---|
| Nextcloud | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 16/20 |
| Proton Drive | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 14/20 |
| CryptPad | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 16/20 |
| Tresorit | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 14/20 |
| Sync.com | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 16/20 |
| pCloud | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 17/20 |
| OnlyOffice | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 16/20 |
| Collabora Online | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | 15/20 |
すべての代替ツール（8）
★★★★★
Client-side encrypted cloud storage integrated with Proton Mail/VPN/Calendar. Zero-access by design.
- クライアント側E2EE
- Secure sharing
- Proton VPN同梱可
- スイス法域
⚠ 無料1GB
★★★★★ OSS
Zero-knowledge browser co-editing for rich text, sheets, kanban, polls, and more. Self-hostable.
- Zero-knowledge
- Rich text/Sheets/Kanban
- 自己ホスト可
- フランスホスト
⚠ 無料枠5GB
★★★★★
Enterprise E2EE sync with Swiss/EU DCs, ISO 27001, granular sharing, and audit features.
- ISO27001
- スイス/EU DC
- 詳細な共有制御
- Outlook/GSuite移行支援
⚠ 高価
★★★★★
Zero-knowledge encrypted cloud with simple UI, fair pricing, and easy file requests and sharing.
- ゼロナレッジ
- カナダ法域
- 手頃な有料プラン
- ファイルリクエスト
⚠ オフィス編集なし
★★★★
Swiss-headquartered storage with Crypto add-on for E2EE, lifetime licenses, and strong media features.
- pCloud Crypto E2EE
- 生涯プラン
- メディアプレビュー
- スイス法域
⚠ E2EEはCrypto追加課金
★★★★ OSS
Microsoft Office–compatible document server with Nextcloud integration, self-host, and SaaS options—strong Google Docs alternative.
- DOCX/XLSX/PPTX完全互換
- Nextcloud統合
- リアルタイム共同編集
- Community Edition無料
⚠ 本格運用はサーバー必要
★★★★ OSS
LibreOffice-based browser office integrated with Nextcloud/ownCloud. Open-source Google Docs alternative with ODF focus.
- LibreOffice互換
- Nextcloud標準統合
- ODFネイティブ
- CODE無料版
⚠ MS Office互換はOnlyOfficeより劣る場合
移行のヒント
- 1 Download Drive via Takeout (enable .docx/.xlsx conversion)
- 2 Export shared folder permissions and rebuild on the destination
- 3 Inventory files that depend on Apps Script or Google-only features
- 4 Test team workflows on Nextcloud+Office or CryptPad before cutover
- 5 Keep encrypted local backups (VeraCrypt, etc.) for critical documents