Skip to content
Tim Borja

Available for contract or direct work · remote worldwide

Mobile apps people open every day.And everything behind them.

I'm Tim, a mobile and full-stack engineer in the Philippines. I ship Flutter and React Native apps to the App Store, Google Play and the web, with the AWS and Postgres backends that run them.

See my appsRésuméPortfolio PDF ↗
Shipped toApp StoreGoogle PlayWeb
15k+
orders
9
campuses
4
native apps
4+
years
Timothy BorjaMobile & full-stack engineer15k+orders9campuses4+years
Manila9:41Replies within a day
Presyo · Oct 6–12▼ ₱1.30Diesel, per liter

Tap an app to open it

Apps

Shipped, and still running.

From a campus delivery fleet on the App Store and Google Play to price data for every Filipino city.

All apps →

Campus Food-Ordering Platform

Four native apps, two web portals and a full serverless backend, live on the App Store and Google Play

9
campuses in production
15,000+
orders processed
219
merchants onboarded
In productionFood & Drink · Marketplace

D-Touch Health Platform

Clinic management SaaS for many independent clinics, with every authorization rule enforced in PostgreSQL

77
RLS policies
660+
database checks
187
Vitest tests
Pre-launchMedical · Clinic management

Presyo

What things cost in the Philippines today, from official government data

11
data sources
1,736
places mapped
2×
automatic updates a day
Presyo: Today's prices near you
Presyo: Pump prices by brand
Presyo: Palengke basket by market
LiveUtilities · Price tracker

Pabili

A pretend shopping app with the features people love about Shopee and Lazada

37
screens
3
platforms, one codebase
25
unit tests
Pabili: Home with deals and games
Pabili: Live selling
Pabili: Slash It
LiveShopping · Social commerce

Groundwork

An AI agent that answers questions from documentation and checks its own citations

50
golden test questions
~190
doc pages indexed
2
self-correction loops
groundwork · localhost:3000
groundwork · agent graph
Groundwork agent graphA question is triaged, then the agent retrieves documents and grades them. If they are not good enough it expands the search and retrieves again. Then it writes an answer and verifies every claim, rewriting if a claim is unsupported, before finishing.questiontriageretrievegradewriteverifyexpandnot enough? search again (max 2)unsupported claim? rewrite (max 1)answer
Both loops are capped, so the agent can't retry forever or run up an API bill.
Source onlyDeveloper tools · AI agent

Mobile craft

The details people feel.

Most of mobile is the hard part a screenshot can't show. These are the ones I've shipped to real users.

Experience

Where the work happened.

Full résumé (PDF) ↗

  1. Independent Full-Stack Developer · Contractor

    Dec 2022 – Present

    Campus food-ordering and delivery marketplace · 4 native apps + 2 web portals · 9 campuses

    • REST and GraphQL over dozens of AWS Lambda services, with EventBridge and Step Functions workflows on DynamoDB.
    • Stripe Connect payments, payouts and deposit holds, plus two campus meal-plan processors with split tender. Found and eliminated a production double-charge caused by retries regenerating the idempotency key.
    • Traced about 4 million promotion reads a day to a client loop and fixed it server-side; added a tiered Google Maps cache.
    • One-command releases of four apps to TestFlight, the App Store and Google Play, with CI/CD and Slack alerts.
    Read the case study →

  2. Sole engineer, clinic management SaaS · D-Touch Health Platform · business project

    Jan 2024 – Present

    4 React Native Web apps · Supabase / PostgreSQL · pre-launch, running on test data

    • Many clinics on one Supabase backend; no app server: 77 RLS policies, 100+ PL/pgSQL functions and 660+ checks for tenant isolation.
    • Exclusion constraints make double-booking impossible.
    • Booking board, tooth charting, billing with GCash / QR Ph, CSV import with dry-run and undo, and a trigger-based audit log. 187 Vitest tests.
    Read the case study →

  3. Mobile App Developer (Flutter) · Achieve Without Borders

    Aug 2022 – Nov 2022

EducationBS Electronics Engineering · San Sebastian College Recoletos de Cavite

2012 – 2017

Skills

Every skill comes with proof.

No logo wall. Each skill links to the projects where I used it, so you can see it working.

Mobile & frontend

Backend & cloud

Data & AI

  • Python data pipelines

    Turning PDFs, CSVs and messy sites into clean, versioned data.

    PresyoGroundwork

  • AI agents & LLMs

    LangGraph agents on Claude that check their own work.

    Groundwork

  • Search & retrieval

    Hybrid vector and keyword search, re-ranking, measured with evals.

    Groundwork

Delivery & operations

Contact

Have an app to build, or one to rescue? Let's talk.

New builds, store releases, backends that need to scale, or a team that needs a mobile engineer. I usually reply within a day or two.

Send a messagetimothyborja28@gmail.com