Andrew Tenno

Staff Mobile Engineer at Meta, promoted from E4 to E6, building iOS and React Native platform infrastructure that powers 500M+ video calls per month across Messenger and Instagram. 11+ years of production experience spanning Swift, SwiftUI, UIKit, React Native, Android (Kotlin + Jetpack Compose), real-time AR rendering, WebRTC video infrastructure, and cross-platform SDK engineering, with security-first mobile architecture across Keychain, certificate pinning, and on-device encryption. Two open-source React Native patches merged to main, technical writing cited by iOS Weekly, and conference speaker on mobile performance at scale.

Staff Software Engineer at Meta (2019-10 – Present)

• Architected Messenger's full AR rendering pipeline (Metal + ARKit + Core ML), shipped as the AR Effects SDK across Messenger, Instagram, and Portal, cutting per-filter development time by 40% and QA surface in half. (AR & Video Calling Platform)
• Built the virtual background segmentation pipeline on the Neural Engine with device-adaptive model routing and thermal-adaptive quality tiers, achieving sub-16ms end-to-end latency on modern devices.
• Led rsys WebRTC integration and built a proactive NWPathMonitor ICE restart state machine that meaningfully reduced reconnect failures and call setup latency.
• Shipped Messenger Group AR Effects (Oct 2021) with ML-ranked prefetch and RTCDataChannel sync, with AI-powered recommendations cutting picker load time significantly for returning users.
• Rebuilt the AR effects UI in SwiftUI using @StateObject, matched geometry, and UIHostingController with Combine state sync, then authored the UIKit integration guide adopted across the calling org.
• Set cross-team technical standards through canonical design docs and bi-weekly architecture office hours across 3 iOS org teams, mentoring 4 engineers with one promoted to E5 in 14 months.
• Authored Messenger's native module suite (iOS RCTBridgeModule + Kotlin Android counterparts), identified a serialisation hotspot through bridge performance instrumentation, and resolved it with RCTEventCoalescer, measurably reducing bridge crossings and JS thread utilisation. (React Native Infrastructure & Android)
• Designed and owned the full mobile CI/CD pipeline covering Xcode Cloud, GitHub Actions, Fastlane Match with App Store Connect API, and Firebase Test Lab, compressing release cycle from 3 days to same-day automated delivery.
• Built the cross-platform RN component library and reduced per-feature UI dev time by 35% across teams shipping simultaneous iOS and Android features.
• Drove Jetpack Compose adoption on Messenger Android, shipping 3 production screens built with Coroutines, StateFlow, and ViewModel, with the Compose migration guide adopted by 2 additional Android teams.
• Co-led Messenger's Swift adoption program using Python and libclang AST tooling, an internal Swift style guide, and a migration framework rolled out across 8 teams, growing Swift LOC from 15% to 45% in 18 months. (Client Infrastructure & Swift Adoption)
• Built a custom ObjC/Swift bridging test harness that surfaced invisible retain cycles, with fixes meaningfully reducing crash rates across core chat flows.
• Built Messenger's client performance telemetry using os_signpost and Meta Scuba integration, adopted by 3 additional Meta iOS apps after Messenger results.
• Conducted Messenger's first systematic VoiceOver and Dynamic Type accessibility audit, with guidelines adopted by 3 iOS feature teams.

Senior Software Engineer at Reddit (2018-06 – 2019-09)

• Restored feed scroll from choppy 45fps to smooth 60fps using Texture (AsyncDisplayKit) off-main-thread layout, with peak scroll memory reduced through lifecycle-aware cell recycling.
• Built an AVPlayer autoplay controller with visibility-based lifecycle, AVAudioSession silent mode respect, and pre-buffering that eliminated video load latency on scroll.
• Delivered VoiceOver coverage across all 8 feed cell types with accessibilityCustomActions for vote, save, and share, marking the first accessibility pass in Reddit iOS history.
• Set up Reddit iOS's first Fastlane CI/CD pipeline covering automated build, XCTest, and TestFlight, significantly cutting release prep time per build.

Software Engineer at Snap (2017-10 – 2018-03)

• Improved Snap's live AR lens pipeline performance by implementing direct zero-copy GPU access via CVMetalTextureCache, keeping 60fps rendering within frame budget on the full device range.
• Built frame latency benchmarking tooling across multiple iPhone tiers, adopted as the camera team's standard pre-release validation workflow for all new lens releases.
• Implemented MTLDevice-based device-adaptive quality tiers (Full, Standard, and Lite), delivering smooth performance across the iPhone 6 through iPhone X range.

Software Engineer II at Ticketmaster (2015-06 – 2017-08)

• Led iOS development of Ticketmaster Verified Fan, a bot-detection and identity-verification flow that protected millions of fan registrations and significantly reduced ticket resale rates on major artist tours.
• Delivered 60fps seat map rendering for 20,000+ seats via CATiledLayer async tile generation and engineered SafeTix rotating barcodes with offline fallback for stadium dead zones.
• Implemented the team's first VoiceOver and Dynamic Type pass alongside the first Fastlane CI/CD pipeline, significantly cutting App Store release preparation time.

B.S. in Computer Science – University of Southern California (USC) (2011-09 – 2015-05)