whoami

elias.jimenez

full_stack_engineer

ai_agents · node · typescript

I build AI agents that do real work.

Technical lead at Geeks5G with 4+ years in TypeScript and Node.js. I design event-driven backends and the integrations that hold them together: AI agents on live phone calls, webhook pipelines across Twilio, OpenAI and Stripe, and multi-tenant SaaS with real billing.

stack.ts

const stack = {
  ai: ['openai', 'vapi', 'tool-calling'],
  backend: ['node', 'nestjs', 'typescript'],
  infra: ['firebase', 'cloud-run', 'docker'],
  data: ['postgres', 'mongo', 'firestore'],
}

./see-work ./download-cv github linkedin

profile.jpg

Medellín, Colombiaavailable

ls ./projects

Selected work

Production systems, mostly backend-heavy. Each one shipped to real users.

Platform Connection

Multi-channel AI agent platform

Geeks5G · Technical Lead

A business configures an AI agent once and it serves their customers across web chat, WhatsApp, SMS and live phone calls. I designed the architecture and built most of the backend.

—AI agents on the OpenAI Assistants API and VAPI, working across every channel without duplicating logic per channel
—Tool / function calling so agents act, not just answer: capturing leads mid-conversation, booking on Google Calendar, transferring to a human when the lead qualifies
—Outbound calling with concurrent calls, answering-machine detection, transfer queues, and a post-call loop that rewrites the assistant's prompt from what happened
—Fully serverless on Firebase Cloud Functions Gen 2 — HTTP webhooks, callable functions, database triggers and scheduled jobs, with Cloud Run for long-running work

TypeScriptNode.jsOpenAIVAPITwilioFirebaseCloud RunNext.js

ProAxis

AI receptionist · pay-per-call marketplace

Geeks5G · Technical Lead

Buyers were losing calls they had already paid for. I built an AI receptionist that picks up what they miss, works out what the caller needs, and hands it to the right person.

—Answers after a configurable ring count, classifies caller intent mid-call, and live-transfers with timeout handling and answering-machine detection
—Agent tools for lead capture and booking — identity and address capture, timezone-safe calendar slots, confirmation emails
—Market intelligence with geo heatmaps and radius search, plus CRM modules for pipeline and commissions

Next.jsNode.jsPrismaPostgreSQLVAPITwilioStripeAWS

Charge Home Solutions

Field-service dispatch platform

Geeks5G · 2026

SMS-driven platform routing EV charger installations to a contractor network. I joined a codebase that had stalled and drove it to completion — around 356 commits and 39,500 lines in four months, closing out both repositories.

—SMS dispatch engine: prioritized offers, fallback broadcast on expiry, reply parsing, scheduled timeouts, and resolution of ambiguous replies
—Cut SMS cost by roughly half — traced inflated billing to en-dash characters silently forcing UCS-2 and doubling segment counts across 26 templates
—Timezone-correct scheduling from customer zipcodes, with quiet-hours gating for US messaging compliance
—Owned invoicing, contracts and a 3-tier Stripe subscription system with trials, ACH and webhook-driven lifecycle

NestJSTypeORMPostgreSQLStripeTwilioReact 19Docker

Real-time Voice Engine

Self-hosted conversational voice service

Personal work · Python

A self-hosted real-time voice service on Pipecat and Twilio Media Streams, integrated into ProAxis call routing so the platform owns its voice stack instead of depending only on a vendor.

—Language policy for inbound calls — detecting and holding the caller's language instead of drifting mid-conversation
—Silence and realtime guard policies so the agent handles dead air, interruptions and edge cases without derailing
—LLM usage tracking for per-call cost visibility

Engine core was extracted from an existing codebase; the policy modules, integration and call logic are mine.

PythonPipecatTwilio Media StreamsOpenAI RealtimeDocker

CashRonald

Personal finance & loan management

Personal product

A product I built end to end, from the design system to the API: tracking personal finances and managing loans — who owes what, what has been paid, and what is coming.

—Personal finance module alongside the full loan lifecycle: clients, loans, payments and activity history
—Its own design system — custom logo, type scale and a dark/light theme designed rather than defaulted
—JWT auth with hashed credentials, schema validation on every endpoint, transactional email

Next.jsReactMongoDBMongooseJWTZodTailwind

cat resume.md

Experience

The short version. The full CV is one click away.

Technical Lead / Full Stack Engineer

Jan 2025 — Present

Geeks5G

—Technical lead across three production products: Platform Connection, ProAxis and Charge Home Solutions.
—Own architecture, data modeling and code quality standards; mentor junior developers.
—Built the AI agent and voice layers, the webhook integration layer, and multi-tenant billing.

Full Stack Developer

Mar 2022 — Dec 2024

Freelance & agency projects

—Delivered MERN applications end to end for small businesses: booking, admin back-offices, e-commerce and PDF generation.
—Clients included Barbería Ollin, Markaribe Group and Viajes Multidestinos.

Full Stack Web Developer (MERN) — Bootcamp

2023

MindHub LA

—Intensive full-stack program. Business Administration degree before moving into engineering.

./download-full-cv

cat principles.md

How I work

I own the whole thing

Architecture, data model, billing, and the production debugging at 2am. I've taken products from zero and picked up one that had stalled and finished it.

I debug what I can't see

You can't put a breakpoint inside a live phone call. Most of my work happens in systems where you reason from logs, replay events, and reconcile state across three providers.

I don't claim what I didn't build

If a teammate wrote it, I say so. That honesty is worth more in an interview and on a team than an inflated list of technologies.

I chase the root cause

A 49% SMS cost cut came from noticing that one invisible character was forcing a different encoding. The obvious fix is rarely the real one.

cat stack.json

What I work with

Tools I have shipped with in production — not a list of everything I have read about.

ai_agents

OpenAI AssistantsOpenAI RealtimeVAPITool / function callingAgent designPrompt iteration

backend

Node.jsNestJSExpressTypeScriptREST APIsEvent-driven architecture

serverless_cloud

Firebase FunctionsCloud RunGoogle CloudDockerGitHub ActionsVercel

frontend

ReactNext.jsTailwind CSSReduxshadcn/ui

data

PostgreSQLMongoDBFirestorePrismaTypeORM

integrations

TwilioStripeWhatsAppMeta Lead AdsGoogle CalendarGoHighLevel

contact.sh

./say-hello

Let's talk

I'm open to remote roles with teams in the US and Europe. If you're building something with AI agents, voice, or messy third-party integrations, that's where I'm most useful.

eliasj.diz@gmail.com linkedin github

Medellín, Colombia · full overlap with US time zones · english B2 · spanish native