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b2b sales · solutions engineering · systems

Juan Castaño

Solutions Engineer · B2B Sales

Medellín, Colombia — remote Spanish (native) · English C2 Professional

I run the commercial process end to end — prospecting, qualification, and closing calls — then design and deliver the systems the client actually needs. I build working proofs of concept during the sales cycle, so prospects see the solution before they buy. Four years of client-facing sales sit on top of seven years building backend, data, and automation systems, so I can scope a problem in the room with a client and be accountable for what gets built.

juan@jcastano.dev LinkedIn

recovered in receivables
$200K+ recovered in receivables Korean Autobody Parts
leads qualified
20,000+ leads qualified Kuberiq
years building / selling
7 / 4 years building / selling since 2019

process

How I work

Different projects, same four steps.

  1. Understand & scope

  2. Build

  3. Revision

  4. Deliver

5 records

Selected work

data.pricing Korean Autobody Parts

Competitive Price Intelligence

The catalog had to stay current with what suppliers and competitors were charging, so pricing decisions were made against the market instead of guesswork.

Built supplier, distributor, MSRP and competitor scrapers, then a reconciliation pipeline that merged fresh pricing into the master catalog while preserving row order.

15,000 parts kept current against four live sources.

  1. One row fails, the run doesn't. The bad row is quarantined and retried; the other 14,999 finish.
  2. Matched on OEM number, not part name. Names differ per supplier. The OEM number doesn't.
  • Python
  • Selenium
  • BeautifulSoup
  • pandas
  • openpyxl

Lead developer

net.touchpad

LAN Touchpad

Controlling a Windows machine's cursor from your phone.

Specified a validated WebSocket message protocol as a standalone package with the gesture engine isolated and independently tested, then constrained the security model deliberately: LAN only, pair before control, strict payload validation, idle and pairing timeouts, and inbound rate limits.

  1. Pair before control. An unpaired client on the same LAN gets nothing — no discovery, no input.
  2. The protocol can't express anything but mouse input. Not blocked at runtime — unrepresentable in the schema.
  • TypeScript
  • zod
  • WebSocket
  • ASP.NET Core
  • React Native
  • Vitest

Protocol, architecture, security model

data.leadgen Kuberiq

Maps Business Scraper

Outbound needs qualified local-business leads at volume.

Built a resumable pipeline with parallel workers and checkpointing so an interrupted run picks up where it stopped, then added geographic enrichment, a qualification scoring pass, and CSV export shaped for CRM import.

Over 20,000 leads collected, enriched and qualified into one pipeline.

  1. Kill a worker mid-run and nothing is lost. Every worker checkpoints; an interrupted run resumes where it stopped.
  • Python
  • Selenium
  • Flask
  • BeautifulSoup
  • geopy

Design and implementation

app.salesStack Kuberiq

Kuberiq Sales Stack

The outreach team worked a daily lead queue across WhatsApp and the browser with no shared system behind it.

Modeled the lead schema and built the mobile-first setter app and the CRM with a companion browser extension, with fixed daily assignment limits and balanced lead distribution.

  • Next.js
  • Supabase
  • PostgreSQL
  • esbuild
  • web-push
  • Vitest
api.elearning PolygonUs

ApiAcademy

An e-learning platform spanning 28 domain modules needed one API behind all of it.

Maintained a layered component architecture separating routing, network and middleware concerns, administered both the MySQL and MongoDB stores, and set up CI/CD to AWS Elastic Beanstalk with a custom nginx configuration.

  • Express
  • MySQL
  • MongoDB
  • AWS S3
  • Swagger
  • GitHub Actions
  • nginx

Also built

Systems
Ulumina — game API and database · Sales Assistant (Telegram, RAG) · Real-time internal chat · speechToText (offline Whisper)
Client websites
Hospitality · Dental and medical practices · Legal practices · Education · Retail and e-commerce
Internal tools
Template generation · Lead scoring and qualification · Document automation · CRM integrations
Experiments
Physics-based interfaces · Trading tools · Speech and audio utilities · Reverse engineering

6 roles

Experience

  1. 2025 — Present

    Founder

    Kuberiq

    • Run the commercial process end to end — outreach, qualification, and closing calls with clients.
    • Build working MVPs and proofs of concept for prospects during the sales cycle — web apps, chat automations, and data pipelines.
    • Scraped, enriched and qualified over 20,000 leads, connecting multiple data sources into one qualification pipeline.
    • Architected the AI agent infrastructure and multi-tenant data models behind client delivery, with row-level security isolating every account.

  2. 2024 — 2025

    Sales & Lead Developer

    Korean Autobody Parts · Florida

    • Recovered over $200,000 USD in outstanding receivables by phone, before escalation to the legal team.
    • Sole handler of one of the company's largest accounts, negotiating high-value orders for late-model repairs.
    • Sold on the floor and drove client acquisition, then built the systems to fix the data problems I saw there firsthand.
    • Kept a 15,000-part catalog priced in real time against competitors and cross-referenced by OEM number.

  3. 2023 — 2024

    Backend Developer

    OptimalClick

    • Contributed to sales funnel construction and built the lead-generation scrapers that fed it, sourcing over 5,000 US leads.
    • Delivered client websites and the backend integrations connecting them.

  4. 2022 — 2023

    Sales & Service Executive

    OptimalClick

    • Drove sales of technical products in cold and warm markets, qualifying new prospects and converting them into long-term customers.
    • Guided clients through software setup, credential management, and troubleshooting.

  5. 2021 — 2022

    Team Leader

    PolygonUs

    • Covered the lead role for over two months after the lead left, as the person with the deepest system knowledge.
    • Ran delivery with agile methodology (Scrum) across three concurrent client projects, coordinating with other areas of the company.

  6. 2019 — 2021

    Backend Developer & Database Administrator

    PolygonUs

    • Built and maintained the APIs and services behind the company's projects.
    • Designed and administered the MySQL and MongoDB databases, with automated backups against data loss.

3 tracks

Capabilities

Commercial

  • Prospecting & qualification
  • Closing
  • Technical discovery
  • Client onboarding
  • Retention
  • Relationship building & negotiation
  • Demos & proof of concept
  • Customer support & troubleshooting
  • Debt collection & claim management

Solutions & Delivery

  • Solution scoping
  • CRM & systems integration
  • Process automation
  • Technical estimation
  • Requirements through to deployment
  • Agile delivery (Scrum)
  • Team leadership
  • AI agent orchestration

Engineering & Data

  • REST & API design
  • Data modeling & row-level security
  • Resumable data pipelines
  • Node.js · TypeScript · Python
  • PostgreSQL · MySQL · MongoDB
  • Supabase
  • Web scraping & market intelligence
  • Data migration & cleaning
  • Docker · AWS · Vercel
  • CI/CD · GitHub Actions · nginx
  • Next.js · Astro · React · Tailwind

live

Sites & demos