David Manzanarez


I joined Amazon as an intern in 2017 and returned to Checkout full-time in 2018. I progressed from Software Engineer I to II, then Senior Software Engineer in 2022. My work grew from building individual checkout components to leading architecture and delivery across teams of 20–30+ engineers. Today I set technical direction across the Checkout organization and still build core systems myself. The purchase flow handles over a million requests a second.

Experience

Amazon · Senior Software Engineer

October 2022–present

Since 2025 I have led Checkout’s AI engineering work. In 2026 my scope expanded beyond a single team to include technical direction across the organization.

  • Engineering agents. Designed and built durable workflows for maintenance tasks such as removing expired feature flags. Each task is validated against an operating procedure and runs as a state machine that records each step, so stalled or failed agent runs can resume without repeating completed work. Outputs are evaluated and require human review before merge. Built MCP tooling over purchase-journey data and service logs, with caching and query limits to protect production systems.
  • Add to Delivery. Set the Checkout architecture and led execution across 20+ engineers in four organizations. Connected delivery data, checkout services, and the customer-facing experience. Later led the expansion to five European marketplaces, working with Product, UX, and Legal on the experience and its requirements.
  • Java microservices migration. Technical lead for a multi-year migration from a monolith involving 30+ engineers, largely completed in 2025. Designed core APIs and plugin interfaces, ran platform experiments, and coordinated rollout while dependent teams continued shipping.
  • Checkout resilience. Reshaping the resilience roadmap around the customer’s ability to complete a purchase, including fallback data and experiences when dependencies fail.
  • Customer-experience (CX) federation. Built a rendering-layer federation prototype that became a funded org program. Backend federation is already in place; this separate program extends team ownership to the customer-facing rendering layer. The goal is for partner teams to ship experience changes as independently owned packages with their own test pipelines. Production rollout is still ahead.

Technical leadership and operations

  • Review architecture designs and 800+ code changes a year across a 50+ engineer organization. Serve as a go-to technical decision-maker, resolving design disagreements and guiding implementation and launch decisions.
  • Lead operational excellence work and handle high-level technical escalations, drawing on experience in production reliability, performance analysis, and peak-event readiness.
  • Run weekly technical consultations serving 100+ engineers annually. Have mentored 4–5 engineers toward senior promotion.

Amazon · Software Engineer II

August 2020–September 2022

  • Led checkout changes across international marketplaces for Brexit, Know Your Customer (KYC) requirements, and India marketplace regulations. Adapted UI, APIs, and data handling with tax and compliance teams.
  • Designed the latency measurement framework for the platform migration and a modular framework separating front-end rendering from back-end data operations.
  • Prepared checkout systems for Prime Day and Black Friday through load, stress, and chaos testing, then automated those tests for future peak events.
  • Reworked onboarding and ran daily office hours as 15+ new engineers joined the team.

Amazon · Software Engineer I

July 2018–July 2020

  • Extended the base chaos-testing framework, adapted it for Amazon Checkout, and integrated it into CI/CD.
  • Built client-side event protection for one-click checkout and coordinated adoption across 24 partner teams.
  • Built a plugin-based internationalization framework for language and currency formatting across all marketplaces.

Amazon · Software Engineer Intern

May–August 2017

Designed and shipped a reusable one-click purchase component proof of concept for integration across shopping pages.

Skills

Languages
Java, Python, TypeScript, JavaScript, SQL, Perl, Bash
Systems and architecture
Distributed systems, microservices, REST APIs, event-driven architecture, API contracts, latency optimization, resilience engineering
Cloud and infrastructure
AWS: EC2, ECS, S3, DynamoDB, RDS, ElastiCache, SQS/SNS, Kinesis, API Gateway, CDK, CloudFormation, CloudWatch, Bedrock. Docker, Linux, Git, CI/CD, GitHub Actions
Frameworks and web tooling
Spring, React, React Router, Hono, Node.js, Vite, Tailwind CSS, Drizzle ORM
Databases
PostgreSQL, SQLite, MongoDB, DynamoDB
Testing and operations
JUnit, TestNG, Cypress, A/B experimentation, load and stress testing, chaos testing, observability, Grafana
AI engineering
Claude Code, OpenAI Codex, Claude API, LLM tooling, agentic AI, MCP server design, durable and idempotent workflows, human review, multi-agent orchestration, prompt-caching cost modeling
Technical leadership
Architecture and code reviews, technical roadmaps, cross-team delivery, mentoring, engineering onboarding

Education

Monterrey Institute of Technology

B.S. Computer Science · 2012–2017

4.00 GPA · Summa Cum Laude · Full-tuition merit scholarship · ACM-ICPC Mexico Regional Finalist, 2015

University of British Columbia

Exchange program · 2016

Machine learning and AI, computer graphics, and astrophysics. Certificate of Academic Excellence; Canadian Government Scholarship.