Open to engineering roles and technical collaborations

Financial infrastructure · Distributed systems · Reliability

I build systems where consistency, traceability and failure behaviour matter — especially when software moves money.

Software Systems Engineer · Financial infrastructure, distributed systems and reliability

Puerto Ordaz, Bolívar — Venezuelaajstalito@gmail.com
Alexander Sánchez Torrejano

About

I work on systems where a mistake does not show up the day it happens, but months later, in a reconciliation nobody can trace back: double-entry ledgers, pay-in and payout rails, migrations that cannot stop the business. Financial infrastructure is the specialisation, but the craft is the same anywhere a system has to explain what it did: invariants that run, a final state for every failure path, and a history you query instead of reconstruct. I pick the tool from the constraints of the problem — Go, Rust, TypeScript or PHP — and I work with AI agents under written limits on what each may decide when the books are at stake.

Puerto Ordaz, Bolívar — Venezuela

Profile
Systems engineeringI build the financial core and lead delivery across backend, frontend and mobile.
Domain
Payments & remittancesDouble-entry ledgers, pay-in and payout rails.
Focus
Money that adds upTraceability, idempotency and reconciliation.
Method
Technology follows the problemI choose tools by the constraints of the system, not by framework loyalty.

Runbook

Engineering domains

Financial Infrastructure

Double-Entry Ledger

Entries that do not balance stay quiet at first. They show up months later, in a reconciliation nobody can trace back any more. So I write debits and credits inside the same transaction, I do not let history be edited, and I keep money in integers. Floats, never.

Pay-in & Payout Rails

Every provider fails its own way and none of them warn you the same. If the rail has no final state for each path, the money sits in no-mans-land, neither credited nor returned, and sooner or later somebody comes asking. I close every path. The odd one too.

Reconciliation & Balance Forensics

A balance that does not add up is rarely the problem. It is the result. You have to walk back to the movement that left it that way, and that part takes more patience than SQL. On screen, a miscalculated balance and a correctly blocked one look a lot alike.

Idempotency & Webhooks

Providers retry. Always. And the same event reaches you through the webhook, through the poller, sometimes even through support, so the idempotency key goes per event and not per request. Put it per request and you credit twice.

Backend

Hexagonal Architecture

As long as the business rule lives inside the controller, switching provider forces you to reach right into the money. I pull the domain out of the framework and keep the ports in plain sight. That way the legacy migrates behind it, with the business still running.

AI Agents

AI Agent Orchestration

An agent writing fast in a money system is not speed. It is surface nobody has reviewed yet. I run them in parallel to cover more ground, but automated review sits inside the flow, not last and optional.

Agent Guardrails & Governance

What matters is not what an agent can do, but what it can decide. Let it propose a change to the charging engine, fine. Let it approve one on its own, no. And I write the limits down, because a limit that only lives in my head is a limit nobody follows.

Persistent Domain Memory

With no domain memory, an agent walks straight back into the trap that already cost a night. It looks at the symptom, takes the same path, ends up in the same place. Every trap I verify gets written down and loads itself into the next session.

Robotics & Data

Data Science

Nobody on the other side wants to see the confusion matrix. They want to know what we are doing and why. The value is in turning data into a decision. The model is just how you get there.

Languages and ecosystem

Technology follows the problem: I choose tools by the constraints of the system, not by framework loyalty.

Backend

PHP · Laravel · Go · REST APIs

AI Agents

MCP Integrations

Frontend

React · TypeScript

Data & Tools

PostgreSQL · MySQL · Git & GitHub · Docker

Robotics & Data

Python · Automation · Robotics

Systems

Selected work

View all projects

Services

Delivery Leadership

I take products from end to end. Scope, planning, keeping people coordinated and keeping whoever has to decide in the loop.

Project delivery · Agile · Stakeholder management · Mentoring

Financial Infrastructure

I design and build the core where the money lives. Double-entry ledgers, wallets, pay-in and payout integrations, and the reconciliation against each provider.

Double-entry ledger · Wallets & holds · Pay-in and payout · Reconciliation

Balance Audits

When a balance does not add up I go looking for the cause, not the symptom. It usually ends in frozen funds, in debt that never made it onto the books, or in a decimal normalised wrong three layers down.

Balance forensics · Production SQL · Root cause · Remediation plan

AI-Augmented Development

I build financial systems with orchestrated AI agents. Not to write code faster, but to cover more ground without dropping the rigour. Automated review, domain memory that survives between sessions, and written limits on what each agent may decide.

Parallel orchestration · Domain memory · Automated integration · Governance & guardrails

Reliable backend systems

A backend that holds up: explicit contracts, a final state for every failure path, and integrations that do not leave an operation half-done when the other side stops answering.

Laravel · PHP · React · TypeScript · REST APIs

Automation & Data Science

I automate processes and analyse data with Python. Scripts, pipelines, scraping and models, for robotics as much as for business.

Python · Data analysis · Automation · Robotics

Experience

Professional path

  1. dic 2019 — Actualidad

    Delivery Lead & Backend Developer

    Cashela

    I lead day-to-day delivery across the Backend, Frontend and Mobile teams and build the financial core of a cross-border payments platform operating in 40+ countries.

    PHP · Laravel · PostgreSQL · React · TypeScript · Delivery

  2. ene 2016 — sep 2019

    Backend PHP Developer

    Freelance

    Development and maintenance of robust, scalable backend systems in PHP.

    PHP · MySQL · REST APIs · Backend

  3. jun 2011 — nov 2015

    Senior Computer & Special Operations Analyst

    SIDOR

    Analysis and support of computer operations and special processes in an industrial environment.

    Operations · Support · Processes

  4. oct 2010 — jun 2011

    Senior Field Technician

    Tesis de Venezuela

    Field technical support and operations in an industrial zone.

    Technical Support · Field

  5. ago 2008 — oct 2010

    Operations Supervisor

    ADM System, CA

    Operations supervision and team coordination in an industrial zone.

    Supervision · Operations

Education

Education & certifications

Education

  • B.Eng. in Computer Engineering

    Instituto Universitario Politécnico Santiago Mariño · 2004 — 2011

    View project

Certifications

  • Certification in Industrial Hygiene & Safety

  • General Electrician

Contact

Let us talk about a system.

I work remotely. Backend, financial infrastructure, or leading delivery for a team.