Full-Stack Engineer · Technical Co-Founder

Vincent Lai.

I take consumer apps from zero to the App Store — full stack, payments included, AI tools development.

8 years of cloud engineering at Rocket Mortgage underpin the work. My daily loop is an AI coding agent, a test harness, and a release build — from design to the store.

Portrait of Vincent Lai

// full stack, zero to store

Projects

From AI agents to app stores.

Agent Harness

Python · MCP · Ollama

A from-scratch agent harness in about 300 lines of Python, with no framework. It has a tool-calling loop, Model Context Protocol (MCP) tool servers added through a JSON entry instead of code, plain-markdown memory, and local or cloud models you can swap mid-conversation. Built to understand what tools like Claude Code and Cursor do under the hood.

Aplotra

Real Estate Deal Agent · Next.js · RAG

Scores how well a property actually fits you. Buyers weight what they care about and enter budget, down payment, rate and location; fit recalculates live as the weights move. The system explains the reasoning — the buyer decides.

Python RAG Agent

FastAPI · Qdrant · Inngest

Upload a PDF, ask questions, get answers grounded in the document with sources cited. Ingest and query run as durable event-driven workflows, so long parses never block the UI, and deterministic chunk IDs make re-ingesting a file idempotent instead of duplicating it.

Deploy AI Agent

FastAPI · LangGraph · Postgres · Docker

A containerized multi-agent service: one natural-language request routes through a LangGraph supervisor to agents that research a topic and send real email. Capability separation is structural — the research agent is never bound to the send tool — and user identity flows through run config the model can't see or forge. Live on DigitalOcean.

Reviews Dashboard

Next.js · TypeScript

A manager dashboard for guest reviews with public property pages showing only approved ones. A channel-agnostic normalization layer keeps the UI from ever knowing a source rates out of 10 — adding a channel is one adapter, not a rewrite.

VentureStack

TypeScript · Bun · MIT

An AI "founding team" for early entrepreneurs: six mentors across twelve venture-building disciplines, delivered as Claude Code slash commands with a private, redaction-aware journal.

Intelligence Emotions

TypeScript · Bun · MIT

A Positive-Intelligence-based mental-fitness coaching stack for Claude Code: five AI coaches running a daily practice loop over a local, event-sourced journal.

Mobile apps — live on the App Store and Google Play

Every one of these went from idea to release build under my hands — architecture, code, payments, QA, and store review included.

Transcriber Voices

Founding Software Engineer

A voice AI app that runs OpenAI's Whisper large-v3-turbo on the iPhone itself: no server, no account, no user data collected. I changed whisper.cpp to do half the work per audio chunk, making transcription real-time even on an iPhone 12 mini. Text appears as you speak, it catches language switches mid-sentence, and it keeps recording in the background with a Lock Screen display.

  • Swift
  • SwiftUI
  • SwiftData
  • whisper.cpp
  • Metal

Cambalachero

Founding Software Engineer

A peer-to-peer marketplace live in Mexico with 9,000 users and growing. Stripe escrow holds the buyer's payment until delivery; scanning a QR code at handoff verifies the sale and releases the seller's payout, with Twilio notifications along the way. Vision models turn a photo into a listing: title, description, category, and price label.

  • FlutterFlow
  • Stripe Escrow
  • QR Verification
  • Vision Models
  • Twilio
  • Firebase

Influenscore

Creator & Developer

Turns live Instagram and TikTok data into a single 0–100 influence score — profile lookups, growth tracking, and shareable score cards. Free with in-app purchases.

  • iOS + Android
  • Live social data
  • In-app purchases

TRUST: Instant Collabs

Technical Co-Founder / CTO

An app that connects creators for instant collaborations. I built the agentic pipeline behind it: it scrapes and profiles creators and businesses across Yelp, their websites, and Instagram at up to 500 concurrent instances for about $0.04 each, with GPT vision writing descriptions, classifying categories, and screening images before a creator reaches a brand.

  • Agentic AI
  • GPT Vision
  • Firebase
  • Algolia
  • Python GCF
  • Stripe
Experience

Fifteen years of shipping, from mortgages to marketplaces.

  1. Nov 2023 — Present

    BLB Digital

    Founding Software Engineer

    • Took Cambalachero from concept to launch on iOS and Android, grown to 9,000 users.
    • Built Stripe escrow payments with QR-code delivery confirmation that releases the seller's payout, plus vision models that write listings from photos.
    • Shipped Transcriber Voices, an iOS app that runs Whisper on-device in real time, even on an iPhone 12 mini.
  2. Nov 2024 — Jul 2025

    TRUST

    Technical Co-Founder / CTO

    • Built an agentic pipeline that profiles creators and businesses at up to 500 concurrent instances for about $0.04 each, using GPT vision to write descriptions and screen images.
    • Scaled Firebase and Algolia search; shipped apps to Google Play and the App Store.
  3. Aug 2011 — Jul 2024

    Rocket Mortgage

    Software Engineer

    • Built a document pipeline ingesting ~200K documents a day on AWS and Kubernetes.
    • Developed .NET 6 APIs and Terraform infrastructure, with Angular front ends and Auth0 access management.
Walkthrough

An AI pipeline that profiles businesses at scale.

  • 3Services in parallel
  • 500Concurrent instances
  • ~$0.04Cost per business

The pipeline chains Yelp → the business's own site → Instagram, extracting contact and social data and pulling about two dozen images along the way.

AI does the judgment work: writing the description, classifying the category, filtering out national brands, and picking which photos are actually good enough to show.

Built at TRUST as technical co-founder. The video is a live demo, end to end.

Contact

Let's build something people use.

San Francisco Bay Area · English / Español / 中文