David Gelhar
Software Engineeer at Dartmouth College
Hanover, New Hampshire, United States
Summary
👤
Senior🎓
Top SchoolDavid Gelhar is a seasoned software engineer with 11 years of professional experience specializing in enterprise directory, authentication, and identity management systems such as LDAP, Kerberos, Shibboleth, and OIM. Based in Hanover, New Hampshire and working at Dartmouth College, he pairs deep protocol knowledge (SMTP/IMAP/MIME) with practical experience in encryption and digital signatures to build reliable, secure infrastructure. He contributes to the popular Apereo CAS project, improving SAML2, Duo MFA integration, Remember-Me behavior, and MongoDB ticket registry stability—work that underscores a focus on robustness and interoperability in single sign-on systems. Colleagues rely on him for bug-driven refactors and subtle fixes that prevent production authentication failures. His background in both academic and open-source settings gives him a disciplined, detail-oriented approach to identity engineering and long-lived systems.
11 years of coding experience
BA, Computer Science, BA, Computer Science at Dartmouth College
Stackoverflow
27,860reputation
2.5mreached
624answers
1question
unix
top-5%
overloading
top-1%
java
top-5%
nsarray
top-5%
network-programming
top-5%
grand-central-dispatch
top-5%
Github Skills (43)
objective-c10
saml10
factor-authentication10
overloading10
user-authentication10
authentication10
spring-boot10
iphone10
unix9
memory-leaks9
ios9
ldap9
java9
mongodb-database9
servlet9
Programming languages (5)
Github contributions (5)
apereo/cas
May 2018 - Aug 2020
Apereo CAS - Identity & Single Sign On for all earthlings and beyond.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:24 commits, 13 PRs, 3 comments in 2 years 2 months
Contributions summary:David's contributions primarily focused on fixing bugs and improving the stability of the Apereo CAS authentication system. They addressed issues related to SAML2, Duo MFA integration, and Remember-Me functionality, ensuring correct behavior and preventing errors. Several commits involved refactoring code and improving the handling of HTTP headers and service configurations. Additionally, the user contributed to improving the overall health and performance of the CAS server through enhancements in the MongoDB ticket registry.
apereosingle-sign-onsso-authenticationauthenticationauthorization
davidgelhar/ExpensifyApp
Jan 2024 - Aug 2025
Welcome to New Expensify: a complete re-imagination of financial collaboration, centered around chat. Help us build the next generation of Expensify by sharing feedback and contributing to the code.
Contributions:82 pushes, 20 branches, 1 tag in 1 year 6 months
Find and Hire Top DevelopersWe’ve analyzed the programming source code of over 60 million software developers on GitHub and scored them by 50,000 skills. Sign-up on Prog,AI to search for software developers.