Cornelius Kölbel
Geschäftsführender Gesellschafter CEO Owner at NetKnights GmbH
Kassel, Hesse, Germany
Summary
🤩
Rockstar🎓
Top SchoolCornelius Kölbel is a seasoned security-focused software entrepreneur with over 12 years of experience building and leading teams in strong authentication and encryption. As founder and CEO of NetKnights, he drives the open-source privacyIDEA MFA project, combining hands-on back-end security engineering with product leadership to deliver flexible, deployable authentication solutions. He previously led product development for LinOTP and Radius Credential Provider at LSE, translating complex security requirements into practical, user-centered systems. Comfortable across full-stack and infrastructure concerns, he contributes to well-known open-source projects (privacyIDEA, InvoicePlane) with a pragmatic emphasis on logging, token validity, API robustness and invoice workflow enhancements. Trained as a physicist, he brings analytical rigor and a clear cultural focus on work-life balance and technical freedom to his teams.
12 years of coding experience
10 years of employment as a software developer
Diplom, Physik, Diplom, Physik at Technische Hochschule Darmstadt
German, English
Stackoverflow
887reputation
132kreached
25answers
15questions
Github Skills (31)
billing10
python10
authentication10
user-authentication10
invoice10
php10
sql10
codeigniter10
api-design9
restful-api9
api-rest9
security9
open-source9
rest-api9
html9
Programming languages (23)
Github contributions (5)
privacyidea/privacyidea
Jul 2014 - Jan 2023
:closed_lock_with_key: multi factor authentication system (2FA, MFA, OTP Server)
Role in this project:
Back-end Developer & Security Engineer
Back-end Developer & Security EngineerContributions:18 releases, 1121 reviews, 4529 commits in 8 years 8 months
Contributions summary:Cornelius contributed to the project by improving the documentation and fixing typos. They were involved in refactoring existing code, adding and testing enhancements to the logging functions. The user added support for handling additional parameters in the API, and incorporated improvements related to security with respect to the authentication, specifically focusing on token validity and authentication.
pythonlockyubikeytwo-factorfactor-authentication
InvoicePlane/InvoicePlane
Jan 2017 - Feb 2018
A self-hosted open source application for managing your invoices, clients and payments.
Role in this project:Full-stack Developer
Full-stack DeveloperContributions:15 commits, 10 PRs, 9 comments in 1 year
Contributions summary:Cornelius primarily contributed to the InvoicePlane project by implementing new features and making enhancements related to product units, quoting, and invoicing. Their work included the creation of database schema changes (new tables and columns), UI elements (forms, tables, and dropdowns), and associated controller logic for managing units. Further contributions involved integrating product units into quotes and invoices, including database and UI modifications, and copying product unit information from the quote to the invoice. The user also addressed a bug and incorporated minor improvements such as year formatting.
paymentscodeigniterinvoiceplaneinvoicesphp
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