FG.
Full Stack Engineer · 6 yrs
Open to work · Remote

I build full-stack systemsthat hold up in productionnot just in staging.

TypeScript, React, and NestJS. 6 years shipping SaaS, ERP, and mobile for teams that run on uptime.

6+ years full-stack/SaaS · ERP · Mobile/Web & native apps/TypeScript end-to-end/Remote — anywhere
Selected Work3 projects
wallet.fwebmaster.com
fwallet-web
01Finance · Web & Mobile

FWallet

A finance app engineered for the edge cases most trackers ignore.

The problem isn’t tracking transactions — it’s doing it reliably at 50k rows, offline, with two devices syncing at once and no data loss on reconnect.

  • Custom sync engine: works offline, reconciles on reconnect without data loss
  • Shared TypeScript core across iOS, Android, and web — one codebase, three platforms
  • Indexed query strategy keeps filters below 100ms past 50k records
  • Background sync with exponential backoff and conflict resolution
ResultSub-100ms queries at 50k+ rows
TypeScript·React Native·Next.js·NestJS·PostgreSQL·IndexedDB
info.kolo-app.com/
kolo-app
02Enterprise · ERP Migration

KOLO-APP

Zero-downtime migration from a brittle monolith to a NestJS service layer.

Strangler-fig migration from a legacy ERP into structured NestJS services. The constraint: production stays live throughout, parity is verified at every step, nothing regresses.

  • Incremental migration using strangler-fig — no big-bang cutover
  • Event-driven service communication via a message broker
  • Integration test suite with parity checks against the legacy system
  • 99.9% uptime maintained throughout the 6-month migration window
Result99.9% uptime during full migration
TypeScript·NestJS·PostgreSQL·RabbitMQ·React·Docker
03SaaS · Multi-tenant CMS

F-CMS

Each tenant gets their own environment. Not a folder — an actual isolated schema.

Most multi-tenant platforms fake isolation with row-level flags. This one uses schema-per-tenant in Postgres — a misconfigured query in tenant A can never reach tenant B.

  • Schema-level tenant isolation — not row-level flags
  • Custom domain routing with per-tenant SSL termination
  • Webhook system for real-time delivery to external consumers
  • Approval workflows, roles, and granular field-level permissions
ResultTrue schema isolation across 100+ tenants
TypeScript·Next.js·NestJS·PostgreSQL·Redis·Docker
cms.fwebmaster.com
monty-cms
How I think

Engineering is more than writing code.

Three principles shaped by real failures — so they don’t have to become yours.

I.

Offline-first isn’t a feature you bolt on. It’s an architectural constraint — get it wrong on day one and you’re rewriting your entire sync layer to fix it.

II.

Code that passes at 100 rows but breaks at 10,000 isn’t passing — it’s a delayed incident. I seed tests at production scale before anything ships.

III.

Row-level multi-tenancy with flags is technical debt disguised as a feature. Real isolation means separate schemas — not WHERE clauses.

Core Stack

TypeScript end-to-end. I choose tools based on what holds up in production — not what’s trending.

Frontend

React · Next.js (App Router) · TypeScript · React Native · Tailwind CSS · Android Studio · Xcode

Backend

NestJS · Node.js · PostgreSQL · Redis · REST · GraphQL · MongoDB

Infrastructure

Docker · AWS · Google Cloud · GitHub Actions · Nginx · Vercel · Turborepo

AI Tools

Claude · Cursor

Get in touch

If your next product
can’t afford to break,
let’s work.

Currently available — response within 24h
freddy12gutierrez@gmail.com

Available for full-time remote roles and long-term contracts. I’m selective — I only take on work I can ship well.