Background & Experience

Square

January 2020 - February 2026

Roles

Teams & Projects

• Tech lead for the Applets framework in Square's Android Point of Sale codebase. The Applets framework is responsible for the following and more:
• Customizable navigation UI and feature discovery
• Bootstrapping the entry point of all top-level features (a.k.a. Applets).
• Composing and layering feature UI together with root navigation chrome and presenting it to sellers (users).
• Permission gating of sensitive features
• Deep link routing
• Led the Applets V2 project, a multi-year initiative in Android POS to fully rewrite the Applets framework in Workflow to directly address performance issues and the increasing maintenance burden of the legacy Square Flow-based implementation (Applets V1).
• Migrated Point of Sale's architecture from a set of many per-feature Workflow runtimes to a single runtime, eliminating around 100ms of overhead when launching modern Workflow-based applets.
• Kept feature teams unblocked by decoupling infrastructure rollout from feature migrations via a compatibility wrapper that simulates the environment of Applets V1.
• Stress tested Applets V2 against an existing >10,000 scenario UI test suite to identify and resolve any functional gaps between Applets V2 and the existing Applets V1 infrastructure.
• Root caused and resolved thousands of feature UI test failures to achieve functional parity with the existing Applets framework, which had been in use for over 10 years and accumulated numerous bespoke behaviors over that timeframe.
• Prevented regressions before and during our production rollout by running all UI tests against both Applets V1 and Applets V2 in CI, ensuring developers were aware of any infrastructure-specific problems their PR may introduce.
• Deployed this infrastructure without seller or developer interruption to five business-critical apps
  • Square Point of Sale
  • Square for Restaurants
  • Square for Retail
  • Square for Appointments
  • Square for Invoices
  , across four deployment targets
  • Square Register
  • Square Handheld
  • Square Terminal
  • Consumer Android (Play Store)
  each.
• Wrote comprehensive migration guides for feature teams to migrate their applets out of the compatibility wrapper and reap the full performance benefits of the new infrastructure.
• Provided Workflow-native deep link support, allowing Applets to define how matching deep links are transformed into props for their Workflow.
• Developed first-class solutions to pain points that were previously solved in a duplicative and inconsistent manner, like passing complex data between applets (i.e. passing a buyer's unpaid cart from the Order Hub to Checkout for payment) or handling deep links that should preempt the overall navigation experience (i.e. triggering seller onboarding or identity verification).
• Proved the impact of Applets V2 by migrating Checkout Applet to run in the root Workflow runtime, resulting in a 23% reduction in P50 launch time and an 11% improvement to in-applet navigation latency on Square Register for our sellers' most-used applet.
• Partnered with owning teams to ship Applets V2 in non-Point of Sale apps like Square KDS, Square Dashboard, and Square Team. Using Applets V2 accelerated feature development, ensured UI/navigation consistency, and allowed those apps to reuse features from Point of Sale.
• Established an org-wide OKR to achieve migration of all applets to Applets V2 root runtime by end of H1 2026, with 80% adoption as of February 2026.
• Partnered with Devices DX to deliver a one-click provisioning system that allows remote/WFH engineers to securely connect their development devices to the Square staging environment.
• Led the investigation of performance issues discovered on Square Terminal and identified improvements to dex2oat configuration to boost performance of SQUID devices.

• Embedded with our sibling team, POS Foundation Android, to advance the performance-focused Applets V2 project before transitioning to that team full-time in June 2023.
• Migrated critical APIs from cold Flows to hot StateFlows to allow consumers to produce a fully populated initial state rather than relying on transient loading states.
• Resolved re-render thrash in Point of Sale's root Workflow runtime caused by partially populated initial states (due to upstream cold Flows), reducing cold boot render passes from >100 to 3.
• Provided extension functions to simplify proper handling of hot StateFlows in Workflows, which were backed by lint rules to ensure the durability of our re-render count improvements.
• Worked with the UI Systems team to improve touch response in widgets across Market, Square's design system.
• Identified and resolved a widespread source of jank in Point of Sale apps through open source contributions to Cycler.

• Worked to unlock a new era of international growth for Square by contributing to new country launches in Ireland, France, and Spain — Square's first international expansions in 5 years.
• Tech lead for Spain rollout:
• Delivered a secure, immutable, and offline-capable invoice numbering system to comply with Spanish tax law without having to compromise on the flexibility of our product offering.
• Worked cross-functionally with product, legal, and other engineering disciplines to define requirements and find solutions for this offline-capable system, for which there was no clear in-market precedent.

• Led a full rewrite of Point of Sale's Settings Applet, the central hub for configuring all features in POS, in Workflow.
• Maintained full compatibility with legacy screens built in Square Flow while providing greatly-improved integration for modern Workflow-based screens.
• Implemented net-new features like search and an enhanced overview-detail tablet UI for faster navigation between top level categories and sibling settings pages contained in a given category.
• Effective application of Workflow's state modeling allowed for high test coverage and explicit handling of corner cases that would otherwise be fundamentally racy.

Guidebook

February 2016 - December 2019

Roles

Projects

• Built and maintained high-impact features for Guidebook's flagship Android app and the hundreds of white-label apps built off of the same codebase:
• Spaces, which allows customers to have a fully-branded experience for their content inside the flagship Guidebook app.
• Mobile Admin, a powerful set of tools that allows organizers to conduct on-the-ground event management from their phone or tablet.
• Attendance Verification, badge scanning tools for session check-in and ticketed admission.
• Limited-Capacity Sessions, which gives attendees verified registrations for an event's most exclusive sessions and waitlist notifications.
• Campus Tours, GPS-based self-guided tours with a built-in audio guide for college campuses.
• Per-User Pricing, verifiable usage metrics that allow smaller events to access premium features at a lower price.
• Calendar 3.0, a complete redesign of the event calendar with an interface that scales from single day to ongoing events.
• Home Feed, a personalized home screen for Guidebook's apps with dynamic content (nearby events, featured events, custom categories), QR code scanning, and passcode entry for private events.
• Deferred Deep Links, allowing first-time users to automatically navigate to their event's guide after downloading the app.
• Developed innovative technical solutions to unlock new product capabilities:
• Chameleon, a build-time annotation processor and code generator that allows for dynamic theming of classic Android Views at runtime.
• Dynamic Permissions, an implementation of Guidebook's robust CMS access control system in the mobile apps, allowing for granular access control to features based on a user's role. Sensitive features are automatically dismissed when a user's permission set changes.
• Improved codebase health through:
• Codebase modularization, breaking up the app monolith into more focused modules. Improved incremental build times by 10x.
• Architectural patterns like Model-View-Presenter and finite state machines, enabling greater testability of core business logic.
• Collaborated closely with designers and product managers to deliver highly-polished features with design flourishes that adapt to Android platform idioms and user expectations.
• Hosted and mentored interns during the summer of 2018 and 2019. Projects included a redesign of the Schedule feature and two new features for Mobile Admin.