Long Doaka Leo · SDE L5
Available for staff-level backend & platform roles

Hi, I'm Long Do.

Friends call me Leo.

Software Development Engineer L5 - building distributed systems at planetary scale.

10+ years shipping resilient backends in Java and Ruby at Amazon, Google, and Cisco. I focus on data consistency, event-driven architecture, and GDPR-safe design for services that serve hundreds of millions of users.

Get in touchView experience
leolongdo@yahoo.comleolongdo.com
10+
Years in industry
500M+
Users served
Amazon · Google · Cisco
Companies
Distributed Systems
Specialty
About

Engineer behind the backends you rely on.

Senior Backend Engineer with 10+ years of experience building high-scale distributed systems at Amazon, Google, and Cisco. Deep expertise in Java and Ruby, with a proven track record of designing public APIs, optimizing database performance at 500M+ user scale, and implementing resilient microservices patterns. Strong focus on data consistency, event-driven architecture, and GDPR-compliant system design.

Planet-scale services

Sync and API layers for 500M+ monthly users, on Spanner and Redis - tuned for tail latency and recurrence semantics.

Resilient by default

Circuit breakers, exponential backoff with jitter, idempotency keys, and multi-region failover with zero-touch recovery.

GDPR-first design

PII-stripping request paths, retention windows, and right-of-access exports baked into the platform from day one.

Polyglot backend

Java + Spring Boot for the heavy lifting, Ruby on Rails where iteration matters, and Go/Python/Node where they fit.

Skills

The stack I ship with.

A pragmatic toolbox built around Java + Spring Boot, but strong across languages, databases, and infra when the job calls for it.

Languages

  • Java (Spring Boot)
  • Ruby (Rails)
  • Go
  • Python
  • Node.js
  • C++

Backend & Distributed Systems

  • Spring Boot
  • REST APIs
  • gRPC
  • Event-Driven Messaging
  • Idempotency Patterns
  • Circuit Breakers
  • Backoff + Jitter

Databases & Caching

  • PostgreSQL
  • Spanner
  • Redis
  • Query Optimization
  • Indexing
  • Data Modeling

Infrastructure & Tooling

  • Docker
  • Kubernetes
  • CI/CD Pipelines
  • Canary Releases
  • AWS Lambda

Observability & Reliability

  • Prometheus
  • Grafana
  • Distributed Tracing
  • On-Call
  • Incident Response
  • Post-Mortems

Practices

  • API Design
  • GDPR Compliance
  • Technical Mentorship
  • System Design
  • Cross-Team Collaboration
Experience

A decade of backends that don't fall over.

From Cisco's developer platform to Google Calendar's sync layer to Amazon's voice commerce stack - here's how it all connects.

  1. Amazon

    Software Development Engineer
    Jun 2022 – PresentRemote

    Voice Commerce Platform

    • Deployed and maintained a Java Spring Boot payment validation sidecar integrated with Redis that enforced idempotency keys, preventing duplicate charges when network glitches caused repeated voice commands.
    • Aligned with product and legal stakeholders on the exact definition of “exactly once” processing for voice-initiated purchase transactions within the Spring Boot orchestration services.
    • Resolved a critical UX dead-end by connecting the Ruby orchestration service to real-time inventory so the assistant suggests alternatives instead of failing.
    • Built a Java canary test framework that caught a formatting error in voice response payloads before it could impact any Echo device model in production.
    • Implemented Java logging filters that redacted PII from voice transcripts and enforced a 30-day retention window to satisfy GDPR requirements.
    JavaSpring BootRubyREST APIsEvent-Driven MessagingRedis

    AWS Lambda

    • Isolated a 200ms cold-start delay in Node.js runtimes to a specific SDK initialization call that could be safely lazy-loaded.
    • Led the live traffic migration to a new Java Spring Boot control plane without dropping a single request or causing a noticeable latency spike.
    • Mentored four junior engineers through code reviews and production post-mortems across Spring Boot and Rails services; two went on to earn promotions.
    • Designed a Java logging layer that automatically redacted sensitive customer data before it reached centralized log storage.
    JavaRubyNode.jsDistributed RoutingControl Plane Architecture

  2. Google

    Senior Software Engineer
    Feb 2019 – Mar 2022London, United Kingdom

    Google Calendar - Core Backend

    • Maintained Java Spring Boot services responsible for event management and synchronization for over 500M monthly active users, backed by Spanner for distributed SQL.
    • Fixed a long-standing enterprise performance complaint by restructuring how Spanner queries expanded recurring meeting series in the Spring Boot sync layer.
    • Designed public REST API endpoints with granular OAuth2 permission scopes after consulting with third-party developers about Java client integrations.
    • Owned the Java backend sync protocol that guarantees offline calendar changes merge correctly with the server without data loss.
    • Implemented a Java data export feature allowing users to download their complete calendar history in a portable format (GDPR right-of-access).
    JavaSpannergRPCREST APIsOAuth2

    YouTube - Video Metadata Ingestion

    • Rewrote the Ruby video metadata ingestion service to process messages more efficiently, reducing the time to update video details after upload.
    • Designed a Redis caching layer in Java Spring Boot that absorbed 80%+ of read traffic for popular videos, protecting Spanner during traffic spikes.
    • Led the post-mortem after a regional outage and deployed circuit breakers with jittered retries in Spring Boot to stop downstream failures from cascading.
    • Built an automated deletion handler in Ruby that fully purges a user's video metadata and watch history upon account closure.
    JavaRubyPub/SubSpannerRedisCircuit Breakers

    Google Cloud AI

    • Deployed a standardized Spring Boot model serving pipeline adopted org-wide to reduce the manual work involved in launching new models.
    • Integrated LLM capabilities directly into the data warehouse using Java services so analysts could query structured data in natural language through SQL.
    • Diagnosed a performance regression slowing inference requests and rewrote request batching logic in Ruby to restore expected latency.
    • Designed a multi-region failover setup in Spring Boot that kept customer-facing gRPC endpoints available during a full zone outage — no manual intervention.
    • Built data-minimization controls into the Java request path to strip PII before it reached the model serving layer.
    JavaRubyDistributed ServingMulti-RegiongRPC

  3. Cisco

    Software Engineer
    Aug 2015 – Jan 2019Dublin, Ireland

    DevNet Developer Platform

    • Built the initial backend platform in Ruby on Rails that launched with 10,000+ registered developers in the first six months.
    • Designed public REST APIs and maintained the OpenAPI specification in Ruby based on direct feedback from external developers integrating with our sandbox.
    • Implemented Redis-based rate limiting in Java to prevent a single misbehaving script from degrading availability for the rest of the developer community.
    • Added Ruby consent management endpoints enabling users to view, correct, or delete their personal data in compliance with GDPR.
    Ruby on RailsJavaREST APIsOpenAPIRedis

    CloudCenter

    • Built Java Spring Boot cost and usage reporting pipelines that pulled data from multiple downstream services and cut report generation time nearly in half.
    • Resolved recurring report failures caused by API throttling by rewriting retry logic in Java to use exponential backoff with random jitter.
    • Designed a Ruby masking layer that anonymized PII before it could appear in a customer-facing cost report.
    • Documented REST API integration patterns in Java and Ruby that became the recommended best practice across Cisco engineering teams.
    JavaRubyREST APIsBackoff + JitterData Pipelines
Highlighted Projects

Ship list.

A selection of the systems I'm most proud of - what they did, at what scale, and with what stack.

Amazon

Voice Commerce Platform

Exactly-once payments

Spring Boot idempotency sidecar backed by Redis that prevents duplicate charges when voice commands retry - paired with GDPR-compliant logging and canary testing for every Echo device model.

JavaSpring BootRedisEvent-Driven
Amazon

AWS Lambda Control Plane

Zero-drop migration

Led the live traffic migration to a new Spring Boot control plane without dropping a single request or producing a noticeable latency spike for customers.

JavaSpring BootDistributed Routing
Google

Google Calendar Backend

500M+ MAU

Core Spring Boot services powering event management and sync for 500M+ monthly users on Spanner, with OAuth2-scoped public APIs and offline-first merge semantics.

JavaSpannergRPCOAuth2
Google

YouTube Metadata Cache

80%+ reads absorbed

Redis caching layer in Spring Boot that absorbed 80%+ of read traffic for popular videos, shielding Spanner during viral spikes - with circuit breakers and jittered retries.

JavaRedisSpannerPub/Sub
Google

GCP AI Model Serving

Multi-region, zero-touch failover

Standardized Spring Boot model-serving pipeline adopted org-wide, with multi-region gRPC failover and PII-stripping data minimization controls on the request path.

JavagRPCMulti-Region
Cisco

Cisco DevNet Platform

10k+ developers onboarded

Initial Rails backend and public REST APIs that launched to 10,000+ registered developers in six months, with Java-backed Redis rate limiting and GDPR consent endpoints.

Ruby on RailsJavaRedisOpenAPI
Education

Where it all started.

BSc in Computer Science

University College Cork (UCC)

2011 – 2015Cork, Ireland
Certifications

Always leveling up.

Retrieval Augmented Generation
Programming with Google Go
Python Certification
SQL for Data Science