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David Dominguez

I architect LLM systems that cut inference costs 12x

— and scale to 800K+ users.

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Senior AI Engineer · LLM Agents & RAG

Bogotá, Colombia · Open to relocation · Remote (UTC-5)

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Experience

  1. Closer AI/ Bogotá

    Cost Cut
    12x
    No Human Needed
    75%
    Eval Pass Rate
    87%

    Sept 2025 — Present

    Co-founder & CTO

    Pre-seed AI sales-agent startup answering end customers on WhatsApp through Meta integrations for 15 paying B2B clients, about 10,000 messages a day at no more than $0.01 per message. Architected a custom multi-agent runtime instead of LangGraph: a state machine that reads intent and journey stage on every turn, scopes prompt, MCP tools and model to that step, calls catalog, payment and memory tools, and hands off to humans only when needed — 75% of conversations never need one. Cut cost per conversation from $0.25 to $0.02 (12x) with per-step routing across 20+ providers, built hybrid multimodal RAG over client catalogs, and grew an eval harness from zero prior data — about 1,000 questions scored by an LLM judge, plus live A/B tests of prompts and models — that took the pass rate from 43% to 87% and gates every release. LLM calls go through PII redaction and zero-retention endpoints. Lead 10 engineers, report to the investors, and still write the core code in TypeScript/Node.js and Python on AWS Bedrock, GCP, Cloudflare Workers, Supabase and Vercel.

  2. MercadoLibre/ Bogotá

    Users Scaled
    800K+
    Uptime Held
    99.9%
    Attributed Revenue
    1%

    May 2024 — Sept 2025

    Technical Lead

    Led the 10-engineer team behind the Affiliates program at Latin America’s largest e-commerce company (NASDAQ: MELI), on Java/Spring Boot microservices, MySQL and React/TypeScript, owning system design, core architecture, sprint delivery and team growth. Scaled it from its first user to 800K+ users in 16 months, reaching 1% of MercadoLibre’s global revenue (attributed), with 99.9% uptime and zero SLA breaches through 800x growth after moving peak-load work to queues and async jobs and adding availability and performance monitoring. Set the team’s testing bar — JUnit and Jest unit and integration suites plus E2E tests gating deploys in CI — and introduced LLM tooling across the team: AI code review on pull requests, LLM-generated unit and integration tests, an internal LLM assistant and AI coding tools for every engineer.

  3. Agua/ Bogotá

    Users
    1M+
    Infra Cost
    ~$0
    Client-Side
    100%

    Aug 2022 — May 2024

    Co-founder & CTO

    Co-founded an angel-funded low-code visual app builder, owning its engineering, hiring, budget and roadmap until winding it down in May 2024, and scaled it to 1M+ users at near-zero infrastructure cost by running it fully client-side, with zero data egress. Built an in-browser bundler and compiler that fetched npm dependencies inside the browser and showed the real React output in the editor, kept fast with WebAssembly, caching and regression tests.

  4. Mr. Pink/ Bogotá

    Engineers Led
    6
    Faster Setup
    2x
    Team Adoption
    100%

    Aug 2021 — Aug 2022

    Lead Developer

    Built client web apps for the agency, then led 6 engineers on its largest account, REEF Technology, a US-based multi-billion-dollar company, after convincing its CTO to hire the agency. Built an automated Kubernetes and CI/CD scaffolding platform that halved project setup time with 100% team adoption, earning the promotion from Senior Developer to Lead Developer in Dec 2021.

  5. Credibanco/ Bogotá

    Dev Pool
    10x
    Terminals
    1000s
    Junior → Senior
    10mo

    Feb 2020 — Aug 2021

    Senior Web Developer

    Built software for one of Colombia’s largest card-payment networks (about 400K terminals). Its proprietary POS hardware required C, so built a Python-to-C transpiler that opened terminal development to the company’s Python developers (10x dev pool), then led the rollout to thousands of payment terminals. Grew from Junior Developer to Web Developer to Senior Web Developer in 10 months.

  6. Freelance/ Bogotá

    Clients
    10+
    To Production
    MVP
    Core Stack
    3

    Oct 2018 — Feb 2020

    Software Developer

    Built Node.js, React and React Native apps for 10+ clients, from MVPs to production platforms — the full-stack depth behind later architecture work at scale.

Work

  1. 01[AGT-001]2025

    Closer AI

    AI sales agent that closes pipeline while you sleep

    Cost Cut
    12x
    No Human Needed
    75%
    Response
    <1s

    Built a custom multi-agent runtime from zero: an LLM-driven state machine that reads intent and journey stage on every message with embedding-based intent classification, injects only that step’s prompt and MCP tools, keeps cross-session memory, and routes each step to a cheaper or smarter model — GPT-4o mini, Claude Opus, Gemini Flash Lite, Grok 4, Llama 3.1 8B, Qwen or DeepSeek, among 20+ providers. Structured outputs, guardrails, prompt caching, streaming, fallbacks and spend caps keep it at $0.02 per conversation instead of $0.25 (12x) with sub-second p95 turns, tracked on per-client cost dashboards. Retrieval is hybrid multimodal RAG over client catalogs — LLM-aware chunking, BM25 plus Vertex AI multimodal embeddings on Upstash Vector, and GCP reranking — so product search covers text and images, with GCP message queues wiring the pipelines. It handles 75% of customer conversations without a human for 15 paying B2B clients, and an eval harness took the pass rate from 43% to 87%.

    • TypeScript
    • Python
    • LLM Routing
    • RAG
    usecloser.ai
  2. 02[LIB-001]2025

    LLM Rate Limiter

    Hard spending limits across every AI provider — zero infrastructure

    Extra Infra
    0
    Overages
    $0
    Provider
    Multi

    Built a TypeScript library that enforces hard spending and usage caps across multiple AI providers — preventing budget overruns before they happen. Supports automatic failover to backup models when limits are hit and recycles unused capacity in real time. Drop-in installation, no servers required. Currently in production at Closer AI and open-sourced.

    • TypeScript
    • Node.js
    • Redis
    • LLM APIs
    github.com/daviddominguezh/llm-rate-limiter
  3. 03[LIB-002]2025

    LLM Markdown WhatsApp

    Ship AI on WhatsApp in one function call

    Function Call
    1
    Config
    0
    Per Integration
    2-3d

    Built a zero-configuration TypeScript library that converts raw AI output into properly formatted WhatsApp messages — handling lists, product cards, links, and Spanish punctuation automatically. One function call replaces days of custom formatting work per integration.

    • TypeScript
    • Node.js
    • NLP
    • WhatsApp
    github.com/daviddominguezh/llm-markdown-whatsapp
  4. 04[PLT-002]2025

    OpenFlow

    Open-source builder for agent-powered SaaS

    Test Files
    225
    Tenant
    Multi
    Open Source
    OSS

    Built a multi-tenant platform for building agent-powered SaaS products: a visual agent builder in Next.js and React, Node.js services on Postgres and Redis, and event-driven scheduled jobs. Every pull request runs format, lint, typecheck and 225 Jest test files in CI. Open source and separate from Closer AI.

    • Next.js
    • Node.js
    • Postgres
    • Redis
    openflow.build
  5. 05[PLT-001]2023

    Agua

    A low-code IDE built on near-zero infrastructure spend

    Users
    1M+
    Infra Cost
    ~$0
    Servers
    0

    Architected the client-side IDE for a low-code platform from the ground up, including an in-browser bundler and compiler that fetched npm dependencies inside the browser and showed the real React output in the editor, kept fast with WebAssembly, caching and regression tests. The fully client-side architecture took the platform to 1M+ users while keeping infrastructure spend near zero.

    • React
    • TypeScript
    • WebAssembly
    • Compiler
  6. 06[SCL-001]2024

    MercadoLibre

    MercadoLibre’s Affiliates program — from first user to 800K, 1% of global revenue (attributed)

    Users
    800K
    Engineers
    10
    SLA Breaches
    0

    Led a 10-person engineering team building MercadoLibre’s Affiliates program on Java/Spring Boot microservices through its full growth phase — from first user to 800K. The program grew to contribute 1% of MercadoLibre’s global revenue (attributed). Owned system design under real growth pressure: queues and async jobs for peak load, observability, reliability thresholds. Zero SLA breaches across 16 months of 800x growth.

    • Java
    • Spring Boot
    • MySQL
    • React
    mercadolibre.com.mx/l/afiliados
  7. 07[SYS-001]2021

    Credibanco POS

    Turned a 10-person bottleneck into a platform hundreds could build on

    Dev Pool
    10x
    Terminals
    1000s
    Deploy
    Nationwide

    Built a Python-to-C transpiler that opened POS terminal development from a small C-specialist team to the company’s broader developer base. Deployed across thousands of payment terminals nationwide. The transpiler removed a structural hiring and knowledge bottleneck that had been limiting the company’s hardware roadmap for years.

    • Python
    • C
    • Embedded
    • Jenkins
  8. 08[DEV-001]2021

    K8s Scaffolding Platform

    Eliminated the hidden tax every engineer paid on every new project

    Faster Setup
    2x
    Manual Steps
    0
    Team Adoption
    100%

    Identified that engineers were rebuilding identical scaffolding from scratch on every client engagement. Designed and built an automated Kubernetes-based platform that cut setup time in half and standardized delivery quality across the full engineering team.

    • Kubernetes
    • Docker
    • Node.js
    • CI/CD

Education

Universidad de los Andes/ Bogotá

Jan 2018 — Dec 2022

Computer Science & Software Engineering (B.S.)

  • QS Top 200 Worldwide
  • #1 in Colombia
  • Top 10 Latin America
  • ABET Accredited

My Philosophy

  1. 01

    Adoption is an engineering problem.

    The hardest tools to adopt are the ones that ignore how people already work. I build to fit existing workflows, existing habits, existing mental models — because the hidden cost of software is never the license. It’s the change management, the resistance, the workarounds your team builds around tools they were told to use.

  2. 02

    Speed is a strategy. Waiting is a decision.

    Every week a tool isn’t in production is a week your team is working around the problem instead of past it. I optimize for sustainable velocity — scoped releases, real users, real feedback — without sacrificing reliability. The compounding cost of delay is invisible until it isn’t. But so is the cost of shipping something that breaks trust.

  3. 03

    Privacy is a design constraint, not an afterthought.

    I treat data privacy as an architectural decision, not a compliance checkbox. At Agua, the fully client-side architecture meant zero data egress — both a product requirement and a privacy guarantee. At Closer AI, I face the inverse problem: third-party LLM calls are inherently data-leaving events. Privacy there means governing what leaves, where it goes, and how long it’s retained: PII redaction before provider calls, zero-retention endpoints, and routing by data sensitivity. The approach changes with the problem. The discipline doesn’t.

Stack

  • TypeScript

    primary language, 8 years deep

  • React

    complex UIs, production-grade

  • Node.js

    APIs at scale, low overhead

  • JavaScript

    browser and Node.js

  • REST APIs

    service contracts at scale

  • Jest

    full coverage, fast feedback

  • MySQL

    relational data, query optimization

  • Python

    AI/ML pipelines, data processing

  • Java

    high-throughput backends

  • PostgreSQL

    relational core of the agent platform

  • CI/CD

    automated pipelines, daily deploys

  • MongoDB

    flexible data models, aggregation

  • Kubernetes

    zero-downtime, auto-heals

  • Sentry

    error tracking

  • Docker

    containerized everything

  • AWS

    production infra, auto-scaled

  • GCP

    ML pipelines, Vertex AI

  • Terraform

    infrastructure as code

  • Datadog

    metrics and alerting

  • AI Agents

    multi-agent runtimes, MCP tools

  • React Native

    iOS + Android, one codebase

  • LLM Routing

    right model, right cost

  • Generative AI

    LLM products in production

  • RAG

    hybrid multimodal retrieval

  • Evals

    LLM-as-judge, release gating

  • Prompt Engineering

    per-step prompts, structured outputs

  • Tool Calling

    multi-step agent workflows

  • MCP

    tools injected per step

  • Machine Learning

    embedding-based intent classification

  • GitHub Actions

    CI on every pull request

David Dominguez

Contact

David Dominguez

8+ years in software engineering and building production AI agents since 2024, as a hands-on co-founder and CTO who still writes the core code. Native Spanish, English at C2. Open to senior AI engineering roles, remote with full US time-zone overlap (UTC-5) or with relocation. If you are building LLM agents that have to work in production at a sane cost, this is a conversation worth having.

l.david.dominguez.12@gmail.com