Open to senior frontend and product engineering roles

I turn complex product systems into clear, fast user experiences.

Senior product engineer with 7+ years across React, TypeScript, and Rails—shipping experiments, platform migrations, and performance work tied to business outcomes.

Senior Product Engineer

See selected work Email me
  • 40%conversion lift
  • 5s → 3sload-time reduction
  • 20m+ → <10mdeployment time

Choose how much to see

Quick overview or full case studies?

Switch any time. The full view adds technical decisions, trade-offs, and more experience details.

Selected work

A few things I’ve built.

Real projects, the technical choices I made, and what changed afterward.

01 Experimentation · Growth

A reusable experimentation system for faster product learning

Designed the React and Rails integration around Segment events and GrowthBook flags so teams could ship, measure, and reverse experiments safely.

The path from product idea to a measurable decision
Event Flag Variant Decision
My role
Frontend architecture and instrumentation
Team
Product, design, marketing, and engineering
Timeline
Iterative releases across one quarter
Constraint
Ship safely while the funnel stayed live
Frontend focus

Typed event contracts, flag-aware React components, reusable experiment wrappers, and QA states for every variant.

  • React
  • TypeScript
  • Rails
  • GrowthBook
  • Segment
40% conversion-rate lift on the winning journey
Open decision trail
Problem

Product education was fragmented and funnel drop-off was difficult to diagnose.

Decision

Standardize event contracts, flag every variant, and verify instrumentation with A/A tests before exposure.

Outcome

A winning experience plus a repeatable experiment path that reduced future setup from days to hours.

  • 100+ analytics events with documented ownership
  • Guardrail metrics and instant rollback through feature flags
  • Server-driven configuration reduced engineering handoffs
02 Performance · Platform

Faster applications without a framework rewrite

Restructured Vue and React delivery paths, removed legacy weight, and improved caching instead of reaching for a disruptive rebuild.

The measured delivery path after the performance pass
01Route split 02Smaller assets 03Edge cache
My role
Performance profiling and frontend delivery
Team
Frontend, backend, design, and product
Timeline
Progressive changes between releases
Constraint
Improve production without a rewrite
Frontend focus

Bundle inspection, route splitting, image conversion, async rendering paths, and cache behavior measured before and after.

  • Vue
  • React
  • JavaScript
  • CloudFront
  • Web Vitals
Before~5s
After<3s
Open decision trail
Problem

Large initial bundles and stale asset delivery slowed high-intent user journeys.

Decision

Profile first, then split routes, remove legacy dependencies, convert images, and tune CloudFront invalidation.

Outcome

About 300KB removed and initial load time reduced from roughly five seconds to under three.

03 Architecture · Delivery

A product-aware platform that made launches routine

Separated React product flows from Rails business logic, introduced typed contracts, and consolidated shared state around predictable boundaries.

Shared product logic replacing one-off launch paths
Questionnaire Product engine Checkout
My role
Frontend architecture and API contracts
Team
Product, medical, design, and engineering
Timeline
Feature-by-feature migration
Constraint
Keep shipping during platform changes
Frontend focus

Typed API adapters, shared React primitives, predictable client state, product-aware Rails services, and query cleanup.

  • React
  • TypeScript
  • Rails
  • REST APIs
  • SQL
3product lines 20+N+1 queries removed Dayslaunch time, not weeks
Open decision trail
Problem

Single-product assumptions were duplicated across onboarding, treatment logic, checkout, and member tools.

Decision

Introduce product-aware contracts and shared primitives while migrating feature-by-feature rather than pausing delivery.

Outcome

Three additional product lines and a launch process measured in days instead of weeks.

More from the product

Identity, payments, and the work that keeps everything running.

Not every useful project gets a launch post. These are systems I built, shipped, or kept alive.

04 Built · Not launched
OAuth Account

Identity · SSO

Google, Apple, and Meta sign-in flows

Built working SSO integrations end to end: provider setup, OAuth callbacks, account linking, sessions, and failure states. The implementation was completed but never launched.

  • Handled callback errors, revoked consent, expired tokens, and hidden Apple email addresses
  • Designed account-linking states so an existing user would not accidentally create a duplicate account
  • Google
  • Sign in with Apple
  • Meta
  • OAuth 2.0
  • PKCE
05 Shipped · Supported
Cart Google Pay Webhook

Payments · Checkout

Payment flows across frontend, API, and processor

Implemented and debugged checkout flows using Stripe, Braintree, and Google Pay—from client-side tokenization through API requests, processor responses, and webhooks.

  • Worked through declines, duplicate callbacks, 3DS/SCA, retries, and idempotency
  • Traced failures across browser state, backend logs, processor dashboards, and webhook delivery
  • Stripe
  • Braintree
  • Google Pay
  • 3DS / SCA
  • Webhooks
06 Production · Ongoing
Error Sentry Fix + verify

Reliability · Debugging

Sentry, bug hunts, and keeping releases boring

Added and used production error tracking to turn vague reports into reproducible bugs, then followed fixes through release and verification.

  • Added useful context, breadcrumbs, release tags, and source maps instead of collecting anonymous stack traces
  • Triaged noisy alerts, found root causes across system boundaries, and confirmed fixes in production
  • Sentry
  • Source maps
  • Logging
  • Bug fixes
  • Release tracking

Frontend lab

I like building the small stuff, too.

This playground is plain JavaScript and CSS. Change the state and watch one component adapt without a framework or a reload.

Accent
Density
Motion
Live component

Good UI should explain itself.

The controls update semantic state; CSS custom properties handle the visual system.

Waiting for input
accent#5b4df5
spacing24px
motionon

Underneath: a tiny state model, accessible controls, CSS variables, responsive layout, and reduced-motion support—the same details I care about in production.

What I build

The frontend work I get excited about.

Not a wall of skill badges—these are the kinds of problems I’ve spent real time solving.

01 / UI

State-heavy product UI

Onboarding, checkouts, dashboards, and forms where the hard part is keeping every loading, error, empty, and success state understandable.

ReactTypeScriptState machines
Checking your payment… Choose a state to update this component.
02 / CSS

CSS with a system behind it

Responsive layouts, tokens, component variants, and motion that stay coherent after the first polished screen.

CSS variablesResponsive UIMotion
03 / EXP

Experiments that don’t rot

Feature flags, typed analytics, reusable variants, and cleanup paths so testing an idea doesn’t leave permanent mess behind.

GrowthBookSegmentEvent design
feature: hero_cta Build something useful. See the work
No visitor assigned yet
Exposures0
Conversions0
{ "event": "waiting" }
04 / PERF

Making slow things feel fast

Bundles, images, rendering, caches, API boundaries, and database queries—measured on the path people actually use.

Web VitalsCloudFrontSQL
Route load 2.8s
Unoptimized path
Main thread vs Web Worker Ready
frames 0

Watch the heartbeat: it freezes on the main thread and keeps moving in the worker.

Behind the interface

I work on the parts users don’t see, too.

Payments, funnels, and sign-in flows are frontend work, backend work, and debugging work all at once.

Illustration of payment requests routed through secure processors, retries, and webhooks
01 / PAYMENTS

Payments and processor integrations

I’ve implemented and debugged payment flows with Stripe and Braintree across the browser, API, processor dashboard, and webhook trail.

  • Client tokenization, hosted fields, payment methods, and server-side transaction handling
  • 3DS/SCA redirects, retries, duplicate protection, failed payments, refunds, and webhook timing
  • Useful customer-facing errors backed by logs that make processor issues traceable
StripeBraintreeWebhooks3DS / SCAIdempotency
Illustration of a questionnaire flowing through cart, checkout, validation, and analytics
02 / FUNNELS

Questionnaires, carts, and checkout funnels

I’ve built multi-step journeys where answers affect what comes next, what can be purchased, and how checkout behaves.

  • Conditional questionnaires, validation, saved progress, and clear mobile states
  • Cart rules, pricing, checkout state, recovery paths, and handoffs between frontend and API
  • Analytics events and experiment flags that show where people get stuck or drop out
ReactTypeScriptStateAnalyticsA/B testing
Illustration of users signing into an application through multiple secure identity providers
03 / IDENTITY

Social sign-in and account linking

I’ve worked through the full SSO path for Facebook and Meta Login, Sign in with Apple, and other OAuth-based providers—not just the button.

  • Redirects, callbacks, state and nonce validation, token exchange, refresh, and session creation
  • Account linking, hidden Apple email addresses, revoked consent, expired tokens, and provider differences
  • Debugging failures across browser storage, provider settings, API logs, and mobile web behavior
OAuth 2.0OIDCAppleMetaSessions

Production debugger

Break a real product flow. Then trace the fix.

Choose a system, inject a realistic failure, and follow what happens across the browser, API, and third-party boundary.

POST /webhooks/stripe Healthy
  1. 01

    Payment method tokenized in the browser

  2. 02

    Processor confirms the payment intent

  3. 03

    Webhook is delivered twice after a retry

  4. 04

    Idempotency key returns the existing order

Experience

Where I’ve worked.

The teams, products, and systems I’ve spent the last several years working on.

Rugiet Health

Senior Software Engineer

– Present · 5 yrs 7 mos

Led React and Rails modernization for a multi-product health platform, pairing platform work with conversion experiments and internal tooling.

  • Owned frontend architecture decisions across React SPA, Next.js, and server-rendered boundaries.
  • Built shared product primitives that reduced launch time from weeks to days.
  • Removed more than 20 N+1 query paths and clarified typed API contracts.
  • Created admin controls that let product teams update content and logic without engineering deployment.

Hivelocity

Senior Frontend Developer

– · Tokyo

Built and improved Vue, React, and Next.js applications while standardizing delivery practices across the frontend team.

  • Reduced deployment time from 20+ minutes to under 10 through GitHub Actions.
  • Improved load times and removed approximately 300KB from production bundles.
  • Mentored six engineers through pairing, code review, and architecture guidance.

How I work

How I like to work.

A few habits I bring to every codebase.

01

Start with the decision

Define the user problem, success signal, constraints, and rollback path before choosing a framework.

02

Type the boundaries

Treat API contracts, analytics events, form input, and third-party data as the highest-leverage places for types.

03

Measure before optimizing

Profile the real path, set a budget, and verify the change in production-like conditions.

04

Ship with an exit

Feature flags, observability, guardrails, and small release slices keep delivery fast and reversible.

Product frontend

React · TypeScript · Vue · Next.js · React Query · Zustand

Backend & data

Ruby on Rails · Node.js · PostgreSQL · MySQL · API design

Delivery & quality

GitHub Actions · AWS · Testing · Accessibility · Web performance

Growth systems

Segment · GrowthBook · Event design · A/B testing · Funnel analysis

Let’s talk

Want to work together?

I’m always happy to talk about frontend work, product engineering, or an interesting problem.

ivanvgcia@gmail.com Download résumé