OpenThesaurus
A libre, self-hostable German thesaurus for synonyms and word associations.
- Data: Self-hosted
- GDPR-native
- EU-owned
- Self-hostable
- Open source
OpenThesaurus is a free, open-source German thesaurus providing synonym lookup and word associations. Developed in Potsdam by Daniel Naber and maintained under GNU AGPL, it is GDPR-compliant, downloadable in multiple formats, and embedded in LibreOffice/OpenOffice by default. Users can self-host the database or access it via a rate-limited public API.
OpenThesaurus is a free, open-source German thesaurus providing synonym lookup and word associations. Developed in Potsdam by Daniel Naber and maintained under GNU AGPL, it is GDPR-compliant, downloadable in multiple formats, and embedded in LibreOffice/OpenOffice by default. Users can self-host the database or access it via a rate-limited public API.
Highlights
- ✓Completely free and open-source (AGPL + CC-BY-SA/LGPL dual licensing)
- ✓Built-in to LibreOffice/OpenOffice, integrated into 1000+ applications
- ✓Downloadable data in multiple formats (text, MySQL, .oxt extension)
- ✓GDPR-compliant with explicit data protection safeguards and 7-day IP retention limits
- ✓Comprehensive API with JSON/XML support and 60 req/min rate limits
- Data location
- Self-hosted
- Pricing
- Free
- EU-owned
- Yes
- Self-hostable
- Yes
Good for
- LibreOffice/OpenOffice users integrating synonym lookup for German document editing without external dependencies
- NLP developers and linguists building German language processing pipelines with self-hosted, redistributable synonym data
- Enterprise German language services (translation, editing) needing GDPR-safe, no-cost thesaurus integrated into workflows
A European alternative to
Frequently asked questions
- Is OpenThesaurus EU-owned and GDPR-native?
- OpenThesaurus — European-owned: Yes; GDPR-native: Yes; self-hostable: Yes; data stored in: Self-hosted.
- How much does OpenThesaurus cost?
- Pricing model: Free. Check OpenThesaurus's own site for current plans and numbers.
- What are European alternatives to OpenThesaurus?
- Compare GDPR-native European alternatives to OpenThesaurus — where each one is built, owned and hosted.
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