Zellyn Hunter
Staff Engineer
Summary
I’m an expert at backend distributed systems, micro-services, Go, and Developer Experience. I am looking for a role with impact, where I can help bring clarity and success to your complex projects.
Work Experience
Square / Block — Sep 2015–Mar 2025
Staff Engineer (Block “L7”)
Frameworks Team: IC — 2023–2025
- Member of Square’s Technical Governance Review Board, reviewing and approving Architectural Decision Records (ADRs) for core technology selection and retirement.
- Plumbed W3C Trace-Context and Baggage through all three frameworks, using OpenTelemetry code-level APIs, enabling traffic diversion to developer microservice instances buried in the RPC call graph.
- Worked with Network, Deployment, Data/Security/Governance teams and AWS Solutions Architect to migrate
sftpandfptsserver functionality to the cloud, ultimately removing one of the last barriers to the full Cloud Migration.
Frameworks Team: Manager — 2019–2023
- Founded, grew, and managed the Frameworks team (5→11 engineers) focused on maintaining and improving core server Frameworks across Go, Java, and Ruby.
- Positioned our team to be critical in the Cloud Migration, working at first to ensure framework compatibility with AWS EKS, and later to develop the process of migrating apps without code changes.
- Architected and led a migration to LaunchDarkly for 20,000+ feature flags, and worked closely with LaunchDarkly to evolve their capabilities to match our scale. This unlocked much safer flag flips, including metrics-gated changes and first-class Segments, again without application-level code changes.
Payments Platform: IC — 2016–2019
- Implemented backend components for Apple Pay and MasterPass integration, focusing on payment gateway communication, allowing Square merchants to support Apple Pay.
- Worked on Chargebacks, documentation, and continuing to steward Go.
Shared Systems: IC — 2015–2016
- Led Go infrastructure development across Square, assuming responsibility for the Go server framework.
- Ported service-to-service retry logic, ensuring that Go applications had parity with Java applications, and allowing developers to reason coherently about retry behavior.
- Unforked a complex and messy internal version of
protobuf/protoc, making upgrades and security patches possible.
YouTube — Aug 2010–Aug 2015
Software Engineer III, Abuse Engineering
- Led development of the client attestation system to verify legitimate YouTube clients reducing automated abuse.
- Built system to score comments for similarity within a 40-minute sliding window, reducing comment abuse.
- Implemented system to identify and discount spammy subscriptions from channel counts.
- Received YouTube Engineering Code Excellence Award alongside two teammates for outstanding technical contributions.
- Ported anomaly detection code to Go, built monitoring dashboards, and implemented slideshow detection algorithms.
Cox Media Group Digital — Nov 2009–Jul 2010
Manager, Software Development
- Led team of five developers participating in building a custom CMS platform for 120+ TV, radio, and newspaper websites.
- Drove technical decision to adopt Python/Django for new CMS development.
- Designed and implemented v1 of the distributed identity system.
- Established Kanban-based Agile development processes focused on flow and cycle time optimization.
Atlanta Journal-Constitution — Oct 2007–Nov 2009
Sr. Web Developer
- Co-designed and implemented new User Registration system with Django integration.
- Developed web applications for data presentation/reporting including executive pay, election results, and Georgia names.
- Built internal tools for news alerts and contest creation, significantly reducing client workload.
- Improved development processes through BuildBot implementation for continuous integration.
Northrop Grumman Mission Systems — Mar 2003–Oct 2007
Software Engineer 4
- Designed and implemented search infrastructure for CDC.gov using Verity and Google Search Appliance.
- Rewrote content inventory backend process, converting from Perl to Java and implementing incremental updates that reduced run time by an order of magnitude.
- Developed enterprise vocabulary solutions working with ontology experts and CDC vocabulary sponsors.
Sapient Corporation — Oct 1999–Feb 2003
Associate, Technology
- Implemented CMS search functionality for UPS.com, integrating Interwoven CMS with Lucene search engine.
- Designed and built discussion boards and online calendaring for cancer.org (American Cancer Society).
Skills
- Understanding complex systems: A desire to understand drives me to investigate and document complex systems and tacit knowledge.
- Languages: Strong in Go, Python, Java. Ok with Javascript. Comfortable with anything.
- Feature Flags: Ask me anything. I have a lot of experience with home-grown solutions, with LaunchDarkly, and with what it takes to migrate from one to the other.
- Infrastructure and Observability: AWS, DataDog, Docker, GRPC, Kubernetes, OpenTelemetry, Protobufs, Terraform, Tilt.
- Miscellaneous: Bazel, CLI tools, DynamoDB, Git (+Jujutsu), Guice, Infrastructure as Code, MySQL, Documentation for humans and AI agents.
- Specialties: Microservices, distributed system design, observability, framework development and maintenance, Developer Experience, teaching and mentoring.
- Long, sweeping migrations: Much of my work in recent years has been in Developer Experience or Platforms, doing long, involved migrations, minimizing impact on product-focused developers.
Side Projects
- Developed
gocool(compiler),go6502(CPU emulator), andgoapple2(Apple II emulator), as well asa2audittests used by most new emulator authors. - Contributed to various open source projects in the Go ecosystem.
- Ported Pikchr (SQLite team’s modern PIC implementation) to Go (
gopikchr), and integrated it with the Goldmark markdown engine and Hugo static site generator.
Interested in
- CRDTs: I would love to get a chance to gain deep working experience with CRDTs.
- AI agents: if you’re measurably improving autonomous coding in complex, tech-debt-heavy codebases, I’d love to help.
- Feature flags: At this point, I know enough to design a flag delivery system from scratch, and it might be fun!
- Location: Remote, in-office in Atlanta, or (ideally), something where both are possible.