LibreOffice PII Anonymization Extension
LibreOffice has an estimated 200 million users worldwide. Governments, schools, and businesses all rely on it. Many use it to avoid costly software licenses. But until now, users had no built-in tool to find and remove personal data from their files.
The old fix was painful. Copy text into a web app. Anonymize it. Paste it back. This kills formatting. It breaks tables, styles, and layout. For complex Writer documents, this does not work.
The anonym.legal extension solves this. It works inside the app. It detects 285+ entity types in Writer, Calc, and Impress.
Install in Under Two Minutes
The extension ships as an .oxt file. This is the standard format for all extensions.
Quick Install:
- Download the
.oxtfrom anonym.legal/api/download/libreoffice - Double-click the file
- Confirm the prompt
- Restart
Manual Install:
- Open the application
- Go to Tools, then Extension Manager
- Click Add, then pick the
.oxtfile - Restart
After restart, the anonym.legal sidebar shows under View, then Sidebar. Sign in to begin.
How Detection Works
Two engines run together to find PII.
| Engine | Finds | Confidence |
|---|---|---|
| Regex | Emails, SSNs, IBANs, credit cards, phone numbers | 1.0 |
| spaCy NLP | Names, organizations, locations | 0.85+ |
Detection runs on the anonym.legal API. Text goes to certified servers in Germany. The servers hold ISO 27001 status. Results return to the extension. No document files are sent. Only text is transmitted.
What each app does:
- Writer: Extracts full text or selection only
- Calc: Reads cells as tab-separated values across all sheets
- Impress: Reads text objects from all slides
Five Anonymization Methods
| Method | Example | Can reverse? | GDPR class |
|---|---|---|---|
| Replace | John Smith → PERSON | No | Anonymization (Recital 26) |
| Mask | john@example.com → j***@e***.com | No | Anonymization |
| Redact | 555-0123 → [REDACTED] | No | Anonymization |
| Hash (SHA-256/512) | SSN → a1b2c3d4... | No | Pseudonymization (WP29) |
| Encrypt (AES-256-GCM) | Name → ENC:xyz... | Yes | Pseudonymization (Art. 4(5)) |
You can mix methods in one pass. Replace names, but encrypt emails. Each entity type gets its own rule.
Format Stays Intact in Writer
This is the key win over copy-paste. The extension keeps all formatting when it replaces text.
Seven font properties preserved:
- Family, size, bold, italic, color, underline, strikethrough
Four paragraph properties preserved:
- Alignment, first-line indent, left margin, right margin
"John Smith" in bold 14pt Times New Roman becomes "PERSON" in the same style. Tables, headers, and footers all stay intact. The extension works inside the document model. It does not export and reimport text.
Note: Format tracking only applies to Writer. Calc and Impress do text-level replacement only.
Review Before You Apply
The preview shows up to 50 found entities. Each row shows:
- Entity type (PERSON, EMAIL_ADDRESS, PHONE_NUMBER, etc.)
- Original text
- Proposed replacement
- Confidence score
Accept or reject each entity one by one. Select all or clear all with one click. Nothing changes until you click Apply. In Writer, Ctrl+Z undoes the last operation.
Presets Sync Across Devices
Save your settings as a preset. Pick entity types, methods, and thresholds. Reuse it across all your documents. It saves time.
On paid plans, presets sync across all anonym.legal products. Set one up in the web app. It appears in the desktop app and the Office Add-in within five minutes. Encryption keys use zero-knowledge wrapping. Only your password can decrypt them.
For more on how the Office Add-in handles the same workflow in Word, see Word Add-in Redaction for Law Firms.
LibreOffice vs. Microsoft Office
Both extensions share the same backend. The same text gives the same results in Writer and in Word. The engine is one and the same.
| Feature | LibreOffice Extension | Office Add-in |
|---|---|---|
| Entity types | 285+ | 285+ |
| Languages | 48 | 48 |
| Methods | 5 | 5 |
| Format tracking | Writer only | Word only |
| Preview | Up to 50 entities | Up to 50 entities |
| ZK auth | Yes | Yes |
| Preset sync | Yes (paid plans) | Yes (paid plans) |
| Platforms | Windows, macOS, Linux | Windows, Mac, Web, iPad |
For a broader look at PII compliance across operating systems, see Cross-Platform PII Compliance: Mac, Linux, Windows.
System Requirements
- LibreOffice 3.0 or later
- Python 3 (bundled with most installs)
- Internet access (for the PII detection API)
- anonym.legal account (free tier: 200 tokens/month)
Get Started
- Download the extension
- Double-click to install, then restart
- Open View → Sidebar → anonym.legal panel
- Sign in
- Open a document, click Analyze, review, click Apply
Full docs: LibreOffice Extension Docs
Sources
- The Document Foundation — estimated 200M+ LibreOffice users worldwide
- anonym.legal PII Detection Testing — 95.5% accuracy, 42/44 independent tests
- GDPR Recital 26 — anonymization removes data from GDPR scope; Article 4(5) — pseudonymization definition