Amara Chen

• Led migration of the payment ledger from a monolithic PostgreSQL schema to an append-only event log, cutting end-of-day reconciliation time from 90 minutes to 6.
• Built idempotency infrastructure that reduced double-charges on flaky merchant integrations by 98% year over year.
• Shipped a rewritten webhook delivery service with exponential backoff and dead-letter queues, achieving a 99.97% SLA across 40M events/month.
• Owned mentorship of two junior engineers through their first on-call rotations and authored internal docs that halved onboarding time.
• Built frontend improvements to the merchant dashboard.
• Collaborated with product designers and QA to audit and improve merchant dashboard accessibility, implementing keyboard navigation and ARIA roles to meet WCAG 2.1 AA compliance.
• Implemented managed/native interop layers using WinRT and COM APIs within the Windows App SDK surface to integrate low-level payment hardware drivers into the desktop client, ensuring compatibility across Windows 10 and Windows 11.
• Profiled and optimised the WinUI merchant desktop client for memory usage and rendering performance, resolving layout jank under high-DPI displays and reducing cold startup time by 35% through lazy initialisation and async data loading patterns.
• Established a UI automation test suite for the Windows desktop client using WinAppDriver, covering critical user flows and integrating tests into the CI/CD release pipeline to gate production builds.

• Shipped a Bayesian search-ranking model that lifted seller GMV 14% in the first month and became the default ranker across the marketplace.
• Owned the checkout API through a Series-B scaling event — carried the service from 200 req/s to 2,000 req/s with zero p99 regression.
• Introduced structured logging + Honeycomb tracing; median debug time on production incidents dropped from ~45 minutes to under 10.
• Co-authored the mobile-first PWA rewrite that grew Android conversion by 22%.
• Established unit and integration test standards for the checkout API, achieving 85%+ coverage and integrating tests into the CI/CD pipeline to gate all production deployments.

• Built the SDK that powers session replay for 300+ B2B customers — TypeScript client + Go ingest pipeline.
• Cut ingest costs 40% by moving hot writes to ClickHouse and cold storage to S3 with a nightly rollup job.
• Wrote the customer-facing SQL query builder used by non-technical PMs to self-serve dashboards.

Focus on distributed systems and machine learning. Undergraduate research assistant in the Networking group, contributing to gRPC congestion-control benchmarks.

Weekend implementation of five rate-limiting algorithms (token bucket, leaky bucket, GCRA, sliding window, adaptive) with side-by-side benchmarks and README diagrams. Ended up on the Hacker News front page.

Toy double-entry accounting library in Julia. Kept just complete enough to file a simple US freelance tax return from parsed bank CSVs.

Talk delivered at QCon San Francisco, 2024.

Open-source financial DB. Merged fixes to the LSM compactor and helped write the replication test suite.