Stefan Arentz
Principal Security Engineer at Wavelo
Old Toronto, Ontario, Canada
Summary
🤩
RockstarStefan Arentz is a Principal Security Engineer with 17 years of hands-on experience blending mobile engineering, cloud infrastructure and security leadership. He helped found and ship flagship Mozilla mobile products — including Firefox for iOS, Firefox Focus, and the Fenix rewrite — and remains an active contributor to those well-known open source projects. As a former Security Engineering Manager at Aiven and long-time Mozilla security tools engineer, he combines people leadership with practical engineering (Python, Go, JS/TS) to harden platforms, build security tooling, and drive compliance such as PCI-DSS and SOC2. Stefan’s background spans low-level systems, distributed services and client-side mobile UI work, giving him a rare full-stack perspective on product security. He thrives in hybrid roles that require both incident response/cloud forensics and shipping durable engineering solutions. Based in Toronto, he also brings entrepreneurial experience from founding and architecting early internet and embedded networking products.
17 years of coding experience
28 years of employment as a software developer
Stackoverflow
34,637reputation
2.7mreached
655answers
20questions
webkit
top-5%
interface-builder
top-5%
nsarray
top-5%
nsdata
top-5%
cocoa-touch
top-5%
uiscrollview
top-1%
Github Skills (59)
kotlin10
wkwebview10
ios10
mobile-development10
ipad10
ui-components10
testing10
user-interface10
browser10
java10
mobile-application10
javas10
component-kit10
go10
sdk10
Programming languages (23)
Github contributions (5)
mozilla-mobile/focus-ios
Nov 2015 - Feb 2022
⚠️ Firefox Focus (iOS) has moved to a new repository. It is now developed and maintained as part of: https://github.com/mozilla-mobile/firefox-ios
Role in this project:
Mobile Developer (iOS)
Mobile Developer (iOS)Contributions:25 releases, 201 reviews, 340 commits in 6 years 4 months
Contributions summary:Stefan primarily contributed to the development of the Firefox Focus iOS application, focusing on user interface (UI) enhancements and bug fixes. Their work included updating various UI elements, such as links, buttons, and setting descriptions, as well as integrating third-party SDKs like Adjust for tracking. The user also made changes to the application's user agent and implemented features related to web cache management, including erasing browsing history.
firefoxbrowserios-appprivacyswift
mozilla-mobile/firefox-ios
Nov 2014 - Nov 2021
Firefox for iOS
Role in this project:Mobile Developer (iOS)
Mobile Developer (iOS)Contributions:14 releases, 43 reviews, 1140 commits in 7 years 1 month
Contributions summary:Stefan primarily contributed to the Firefox for iOS project, making changes focused on UI and application logic. Their commits demonstrate a focus on the integration of features within the application's core user experience, as evidenced by the implementation of the Send To UI, and contributions to the Share Extension and Reader Mode. This suggests a role that is primarily focused on client-side iOS development.
firefoxbrowserios-appswiftios
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