Timothy CevallosAvailable for work

I build systems that handle real traffic.

Full-stack engineer, eight years in. I've kept high-traffic platforms online for 100k+ people a day, and I now build RAG pipelines, multi-tenant SaaS, and analytics tooling on Next.js, Laravel, and Postgres.

  • 01Production systems, not prototypes — shipped, monitored, and maintained.
  • 02Performance and accessibility treated as requirements, not polish.
  • 03Comfortable owning a feature end to end, from schema to CSS.
100k+
Daily visitors served
8+
Years shipping
50+
Projects delivered
Technologies I work with: Next.js, React, TypeScript, Laravel, PHP, PostgreSQL, RAG Pipelines, Qdrant, pgvector, Stripe Connect, NestJS, Python, FastAPI, Redis, Docker, WordPress, Tailwind CSS, REST APIs
01 — Background

About

I’m a self-taught full-stack web developer with extensive experience in building web applications and responsive user interfaces. I love solving problems of any scale and always find solutions, even to the most complex challenges.

In my free time, I seek balance in all aspects of life. You’ll find me experimenting in the kitchen, tending to my garden, or staying active and fit.

01
Frontend
React · Next.js · TypeScript · Tailwind
02
Backend
PHP · Laravel · NestJS · FastAPI
03
Data
PostgreSQL · Redis · pgvector · Qdrant
04
AI
RAG pipelines · vector search · multi-LLM
02 — Capabilities8 core

Technical Skills

From building scalable web applications to implementing AI-powered solutions, here's my technical toolkit.

3years
Next.js
Full-stack React framework
5years
React
Component-based UI library
3years
TypeScript
Type-safe JavaScript
8years
PHP
Server-side scripting
5years
Laravel
PHP web framework
8years
WordPress
CMS & custom development
4years
PostgreSQL
Advanced relational database
4years
Tailwind CSS
Utility-first CSS framework

Also proficient in

Frontend

  • JavaScript
  • HTML5
  • CSS3
  • React
  • Next.js
  • TypeScript
  • Tailwind CSS
  • Alpine.js
  • jQuery
  • SCSS
  • Bootstrap
  • Responsive Design
  • WCAG/Accessibility

Backend

  • PHP
  • Laravel
  • WordPress
  • Node.js
  • NestJS
  • Python
  • FastAPI
  • REST APIs
  • GraphQL

Databases

  • PostgreSQL
  • MySQL
  • Redis
  • Drizzle ORM
  • Prisma
  • pgvector
  • Qdrant

AI & ML

  • OpenAI API
  • Claude API
  • RAG Pipelines
  • LangChain
  • Vector Search
  • Embeddings
  • Prompt Engineering

DevOps & Tools

  • Git
  • Docker
  • Vercel
  • AWS
  • CI/CD
  • Linux

Integrations

  • Stripe
  • Stripe Connect
  • Clerk Auth
  • Auth.js
  • SendGrid
  • Google APIs
  • Meta APIs
  • Webhooks
03 — Selected work

Selected Projects

Four builds that show the range: an AI support platform, a payments SaaS, an operations dashboard, and a platform that served six figures of traffic every day.

01
AI/ML2025Architecture & build

AX AI Support Platform

Production-grade RAG-powered AI support platform with vector search, multi-LLM support, and intelligent content recommendations for Athlean-X customer support.

Next.js · FastAPI · Python · Qdrant · PostgreSQL · Redis · Docker · LLMs · +3

LLM providers
3
LLM providers
Hybrid rank fusion
RRF
Hybrid rank fusion
Vector stores
2
Vector stores
02
SaaS2025Solo build

Paganki SaaS Platform

Multi-tenant SaaS platform for invoice management with Stripe Connect integration, subscription billing, and merchant onboarding across multiple languages.

Next.js · NestJS · Prisma · Stripe Connect · PostgreSQL · Clerk · TypeScript · Docker · +1

Live site
Languages shipped
5
Languages shipped
Connect payouts
Stripe
Connect payouts
Tenant architecture
Multi
Tenant architecture
03
SaaS2025Full-stack

Parking Operations Analytics

Full-stack financial analytics dashboard for multi-location parking operations, enabling real-time transaction synchronization, shift-level revenue tracking, and comprehensive monthly reporting.

Next.js 16 · React 19 · TypeScript · Tailwind CSS · Drizzle ORM · PostgreSQL · Auth.js · Redis · +2

Transaction sync
Real-time
Transaction sync
Revenue granularity
Shift
Revenue granularity
Garage support
Multi
Garage support
04
Websites2016—2023Full-stack

Athlean-X

Developed a custom Laravel-powered backend with a fully bespoke cart and product system. Optimized for performance, scalability, and user-friendly e-commerce experiences.

Laravel · WordPress · JavaScript · PHP · HTML · CSS · jQuery · MySQL · +8

Live site
Daily visitors
100k+
Daily visitors
Lighthouse points
+20
Lighthouse points
Cart & checkout
Custom
Cart & checkout
04 — Experience

Where I have worked

Eight years across enterprise data platforms, a direct-to-consumer business at scale, and independent client work.

2024 — Present

Freelance Full-Stack Developer

Self-Employed

Building production-grade SaaS platforms, AI-powered applications, and analytics dashboards for clients using modern tech stacks including Next.js, NestJS, and AI/LLM integrations.

  • 01Built multi-tenant SaaS invoicing platform with Stripe Connect
  • 02Architected RAG-powered AI support system with multi-LLM support
  • 03Developed real-time analytics dashboard for parking operations

Next.js · React · TypeScript · NestJS · PostgreSQL · Stripe · AI/LLMs · FastAPI

2022 — 2024

Senior Web Developer

Nielsen

Led frontend development for enterprise data visualization platform, creating dynamic Gutenberg blocks and improving performance.

  • 01Built custom Gutenberg blocks for data visualization
  • 02Improved site performance and accessibility scores
  • 03Collaborated with product teams on feature delivery

WordPress · PHP · Alpine.js · Tailwind CSS · Chart.js · Gutenberg

2017 — 2022

Full Stack Developer

Athlean-X

Managed full-stack development of high-traffic e-commerce and content platforms serving 100k+ daily visitors.

  • 01Built scalable Laravel e-commerce systems
  • 02Maintained WordPress blog with custom features
  • 03Developed progressive web application portal

Laravel · PHP · WordPress · JavaScript · MySQL · Zend Framework

05 — Contact

Let's build something that lasts.

Open to freelance projects and full-time roles. Tell me what you're working on and I'll come back with a straight answer on scope and timeline.