Open to opportunities

Brian O'Neill

@brianoneill

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Senior full-stack engineer delivering reliable, performant products with product-minded technical leadership.

Ireland

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What I'm looking for

I seek a product-focused engineering role where I can own end-to-end systems, improve reliability and performance, mentor engineers, and deliver measurable user impact.

I am a senior full-stack engineer with 7+ years building reliable, high-performance web and mobile systems and leading cross-functional initiatives from ambiguity to delivery. I combine strong technical judgment with product thinking to solve the right problems, not just ship features.

I've improved performance and reliability across stacks — cutting API latencies, page load times, and infra costs while raising user engagement and meeting completion. I design observability, SLOs, and runbooks to stabilize incidents and reduce MTTR.

My work spans frontend (Next.js, React), backend (Node/NestJS, GraphQL, tRPC), data stores (Postgres, Redis, Elasticsearch), and cloud infrastructure (AWS, Kubernetes, Terraform), with hands-on experience in AI integrations (OpenAI, pgvector) and robust CI/CD pipelines.

I mentor engineers, run design reviews, and introduce engineering practices (feature flags, contract tests, deterministic test fixtures) to reduce risk and improve delivery velocity. I seek to join teams where I can pair deep technical ownership with product impact.

Experience

Work history, roles, and key accomplishments

Current

Senior Full-Stack Engineer

Current

Parabol, Inc.

Oct 2024 - Present (1 year 4 months)

Led performance and reliability initiatives for Parabol's Next.js product, cutting board load time ~42% and p95 API latency from 780ms to 420ms while reducing incidents and deploy lead time and delivering AI meeting summaries that increased weekly usage ~17%.

Next.js React TypeScript Redis PostgreSQL OpenTelemetry AWS

Full-Stack Engineer

Happeo

Jan 2022 - Sep 2024 (2 years 8 months)

Improved search relevancy +22% and Core Web Vitals to 'Good' for 95% of pageviews, slashed p95 GraphQL latency from 900ms to 410ms, and instituted SLOs and deploy practices that reduced incidents and accelerated deploy frequency.

Next.js React TypeScript GraphQL PostgreSQL OpenSearch Redis Kubernetes OpenTelemetry

Backend Engineer

Mika Health

Oct 2019 - Dec 2021 (2 years 2 months)

Optimized APIs and caching to grow daily active sessions ~19% and reduced crash-loops while building Kafka job processing with idempotency and adding NLP classification that increased CTR ~12%.

TypeScript PostgreSQL Redis Kafka Python OpenTelemetry Terraform Elasticsearch

Android Developer

Polarsteps

Jun 2018 - Sep 2019 (1 year 3 months)

Reduced crashes per 10k sessions 47% and improved photo sync reliability to 99.4% by implementing WorkManager-driven resumable uploads, memory optimizations, and CI-driven release processes.

Kotlin Coroutines ROOM Jetpack WorkManager Retrofit Fastlane

Software Engineer Intern

SoapBox Labs

Jan 2018 - May 2018 (4 months)

Expanded regional speech dataset and accelerated dataset validation 6x, built automated audio quality checks and test suites that improved partner integrations and model training insights for European launch.

Python JavaScript Pytest REST APIs Audio Processing Automated Testing