Lex Santiago - Professional API Developer

Lex Santiago

Engineer / Creator

I build AI that handles the boring stuff — so people can focus on what matters.

College engineer building tools that actually solve real problems.

Currently building: AI Receptionist v2.0
Currently accepting 2 new clients for Q4 2025

My Learning Path (so far)

Building in public. Shipping what I actually use.

  1. 📚 2023

    Flask API

    First real REST routes. Learned how HTTP verbs actually behave.

    What clicked: "Working with Flask taught me about how to level up my website game and helped me level up my coding toolkit."
    Flask • REST • JSON
    🔧 Lesson: "Forgot to close DB connections → learned about context managers the hard way."
  2. 🚀 2024

    FastAPI + Twilio Bot

    Async, env vars, and deployment pain. This showed me that AI calls are really just glorified FastAPI chatbots.

    What clicked: "Getting an OpenAI developer key was like getting the keys to the AI kingdom. BackgroundTasks > while True loops."
    ✅ Result: Handled real client calls without babysitting.
    FastAPI • Twilio • Async • Deploy
    🔧 Lesson: "env vars broke prod once → fixed with .env + secrets manager."
  3. 🤖 2025

    AI Receptionist

    RAG + voice routing. This one saved people time + money.

    What clicked: "Queue + fallback to human = no missed calls."
    ✅ Result: Businesses stopped losing after-hours opportunities. Cut missed calls by 90% and reduced staffing costs.
    RAG • OpenAI • Voice • Production
    🔧 Lesson: "First version had 2s API cold start → optimized to <1s with connection pooling."
    Next up: v2 with multi-tenant auth, Stripe billing, SMS fallback

still learning, always building.

Projects That Started with a Simple Question

"How can I make this easier?"

AI Receptionist for Small Businesses

Saves time and missed calls. 24/7 AI phone system that handles customer inquiries, schedules appointments, and provides information so business owners can focus on their core operations, not their phones.

FastAPI Twilio OpenAI GPT RAG Redis PostgreSQL
Impact: Started with a simple question: What if small businesses never missed a call? Now saves businesses 20+ hours/month and reduces operational costs.

DonXera Website Demo

Built for my cousin's resell store in Royal Palm Beach, Florida. Real-time inventory tracking synced with SAP ARP and Lightspeed POS. Handles 140+ SKUs with smart brand search and automated reconciliation across multiple locations at 10131 Southern Blvd, Royal Palm Beach, FL 33411.

Python Flask SAP ARP Google Sheets API Lightspeed API PostgreSQL Docker
Impact: Turned a 4-hour weekly reconciliation task into a real-time automated system. No more manual counting. Instant stock visibility across all locations.

What Clients Say

"Alex built me an AI receptionist that actually works. I can focus on my clients instead of answering the phone all day. It's like having an extra pair of hands."

Maria Torres

Owner, Bella Vista Salon

"He explained everything in plain English — no tech jargon. The AI handles our after-hours calls perfectly. Simple solution, big impact."

David Kim

Operations Manager, Kim's HVAC Services

"We went from chaotic spreadsheets to a clean system that just works. Alexander walked me through every step. Real talk: this saved us hours every week."

Alex Martinez

Store Manager, DonXEra Streetwear

Hey, I'm Lex

I'm a college engineer who builds systems that think, so people don't have to stress.

I grew up in a Spanglish household where clear communication wasn't always easy — now I build tech that's simple, accessible, and human. Every API I design has one goal: make life easier, one connection at a time.

Learning from NJIT mentors Mark Chiusano and Keith Williams, I'm building tools that connect people and ideas.

Learning to code

📚 Where it started

Building projects

🚀 Building real projects

"I saw business owners missing calls while serving customers. Managers stuck on the phone instead of running operations. Companies losing opportunities after hours. So I started building AI that replaces expensive staff positions — giving businesses the opportunity to save money while never missing a call."

Expertise & Technologies

🚀
FastAPI
Backend Framework
2 years
🐍
Python
Core Language
2 years
🌶️
Flask
Web Framework
2 years
🤖
OpenAI API
AI/ML
1 year
🧠
RAG Systems
Vector DB
1 year
📞
Twilio API
Voice/SMS
1 year
🏢
SAP ARP
Enterprise ERP
1 year
🐘
PostgreSQL
Database
2 years
Redis
Cache/Queue
1 year
📊
Google Sheets API
Integration
2 years
💳
Lightspeed POS
Retail Integration
1 year
🐳
Docker
DevOps
2 years
🎨
HTML/CSS
Frontend
2 years
🅱️
Bootstrap
UI Framework
2 years
🎮
Lua + Roblox
Game Dev
2 years
🌐
ngrok
Tunneling
1 year

Professional Certifications

  • FastAPI Production Best Practices
  • Twilio Voice & SMS Integration Specialist
  • SAP ARP Enterprise Inventory Automation
  • OpenAI API & RAG Systems Architecture
  • Python Full-Stack Development

💬 Talk to Me About Your Idea

I'd love to hear what you're building. Let's see if I can help.

🎙️ Send Me a Voice Message

Or just drop a quick message below — no pressure, just conversation.

Quick Info

Response Time: Within 24 hours

Currently accepting 2 new clients for Q4 2025

Location: Remote (Global)

Consultation: Free 30-min call

📸 Follow My Journey
\n \n "