About jSentinel
Security you can trust because you can read it. What started as an open-source Java security library is now an independent, EU-based company with five lines of work.
What we do
Open Source
EUPL-licensed, mutation-tested security libraries — flagship jCustos, with more projects to come.
Security Consulting
Application & Java security: integration, audits, bootstrap hardening, architecture — a direct line to the author.
AI-Security
Securing RAG & LLM systems — threat modeling, prompt-injection & data-exfiltration defenses, guardrails.
jSentinel AI
Building AI, secure by design — AI advisory, AI apps, corporate LLMs, RAG systems & personal assistants, self-hosted or EU-cloud.
Academy
Developer training — Secure Coding in Java and AI-Security for Developers, on-site, live-online or on-demand.
Principles
Evidence over claims
Mutation testing, standards mapping (OWASP ASVS / NIST / 40 CWE) and a CycloneDX SBOM — verifiable, not asserted.
Open core
The complete security core stays EUPL 1.2 — read it, run it, fork it. The commercial Enterprise edition adds the operations and forensics modules for teams that must prove what their security layer did; consulting and support come on top.
🇪🇺 Made in the EU
Independent, EU-based maintenance. Privacy by default — no third-party CDNs or trackers on this site.
The founders
Two brothers, one bar for security. jSentinel is founded by Sven and Benjamin Ruppert.
Sven Ruppert
Co-founder · Developer Advocate — 30+ years of software development & DevSecOps; Java expert, conference speaker & security-library author.
Benjamin Ruppert
Co-founder · Security Sales Expert — 20+ years in the IT-security channel; enterprise sales & channel management.
jSentinel Ltd.
🇪🇺 Company details
- Legal form
- Private company limited by shares
- Jurisdiction
- Cyprus 🇨🇾 (EU)
- Directors
- Sven Ruppert · Benjamin Ruppert (to be confirmed on registration)
- Registration no.
- to be published
- Registered office
- to be published
- VAT / VIES
- to be published
Full imprint & legal terms: Legal & Imprint.