Jonathan Westerfield

Backend & Platform Engineer

I'm a backend and platform engineer with 5+ years at Amazon, building Java and Python services, APIs, and reliable distributed systems.

I'm targeting backend and platform engineering roles.

View selected work Download résumé
  • 5+ yearsBuilding production systems at Amazon
  • Java + PythonBackend services, developer tools, and APIs
  • 100+ endpointsIn a diagnostic API platform I owned
  • 8+ teamsUnblocked by centralized fleet-test telemetry

Selected work

Selected work, grounded in outcomes.

Software Development Engineer II, Amazon — Annapurna Labs December 2022–July 2025

Making fleet tests observable with CloudWatch

Replaced crash-prone local test logs with centralized CloudWatch telemetry for fleet-wide accelerator hardware investigations.

Impact: Unblocked debugging for more than eight engineering teams and reduced cross-organizational investigation time to resolution by more than 90%.

  • AWS CloudWatch
  • Observability
  • Go
  • Linux logging
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Independent Software Engineer July 2025–Present

Librarian: a local-first retrieval platform

Building an open-source system that turns an EPUB library into a source-grounded, local question-answering experience.

Impact: A public, inspectable implementation of an end-to-end retrieval system, from ingestion and storage through API and browser workflows.

  • Python
  • FastAPI
  • SQLite
  • Docker Compose
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Experience

A record of building production systems.

  1. Librarian

    Independent Software Engineer July 2025–Present

    Building an open-source, local-first retrieval platform for long-form EPUB libraries.

  2. Amazon — Annapurna Labs

    Software Development Engineer II December 2022–July 2025

    Built diagnostics, APIs, and validation tooling for accelerator hardware platforms.

  3. Amazon Ads

    Software Development Engineer May 2021–December 2022

    Delivered Java services and platform capabilities for pricing experimentation and auctions.

  4. AWS Directory Service

    Software Development Engineer June 2020–May 2021

    Improved security, monitoring, and production change-management tooling.

Approach

How I work.

I build backend services and platforms where clear interfaces, useful diagnostics, and repeatable delivery help teams operate complex systems with confidence. My work spans Java service and API-contract changes, production validation and debugging, and developer-facing tools. I'm currently building Librarian, an open-source local-first retrieval platform in Python and FastAPI.

Contact

Continue the conversation.

I'm open to backend and platform engineering conversations. The quickest ways to reach me are email or LinkedIn.