Portrait of Alexis Vargas

Alexis Vargas

Software Engineer · Backend & Full-Stack (Python/Django, Vue, Flutter)

  • Sydney, NSW, Australia
  • English (professional), Spanish (native)
Open to backend and full-stack roles in Sydney
Email me Download CV GitHub LinkedIn

About

I build web, mobile and backend software end to end. Since 2025 I have designed, built and run Caissify on my own: a Django API with real-time features, a Vue web app, Flutter apps on the App Store and Google Play, and a Rust desktop app.

Before that, I spent ten years building production web applications and APIs in PHP/Laravel and Ruby on Rails.

I work with AI coding agents (Claude Code, Cursor) every day, with written rules, CI and code review, so I move fast without losing quality.

Chess is where Caissify started: I am a chess player and coach, which gave me the domain knowledge behind its open-source FIDE pairing engine.

  • 10+ yearsbuilding production web software
  • 4 platformsweb, iOS, Android and desktop, built solo
  • 10,000 tournamentspairing engine checked against FIDE's reference engine

Projects

Caissify

Jun 2025 – Present

Founder & Lead Engineer (self-directed)

Chess learning and tournament platform that I designed and built as the only engineer: about 2,000 commits across 12 repositories since June 2025.

  • Django 5.2 / DRF API with about 330 API operations and about 1,050 tests, running on Railway as four services from one Docker image (web, Celery worker, Celery beat, WebSockets). CI runs the tests against PostgreSQL and Redis.
  • Real-time live lessons and games on Django Channels: room state in Redis, every event stored in a PostgreSQL event log, and state rebuilt from the log after a restart.
  • Flutter app for iOS and Android, live on the App Store and Google Play, in English and Spanish, with push notifications and on-device Stockfish analysis.
  • Vue 3 + TypeScript web app with Stockfish compiled to WebAssembly in a Web Worker and an OpenAPI-generated API client.
  • Offline-first desktop app for tournament arbiters that syncs with the API through idempotency keys, so a retried request never applies twice.
  • Own Glicko-2 rating implementation for puzzles and players, checked against Glickman's published worked example.
  • Python
  • Django
  • Django REST Framework
  • Celery
  • Django Channels
  • PostgreSQL
  • Redis
  • Vue 3
  • TypeScript
  • Flutter
  • Rust
  • Tauri
  • Docker
  • Railway
  • GitHub Actions
Visit site ↗ App Store ↗Google Play ↗

caissify-pairings: open-source FIDE pairing engine

Apr 2026 – Present

Author and maintainer (open source)

Pure-Python library for chess tournament pairings, published on PyPI (12 releases).

  • Implements the FIDE Dutch Swiss system with Baku acceleration, FIDE Berger round-robin and a casual Swiss mode, plus TRF16 import and export.
  • Pairs each round with maximum-weight matching (Edmonds' blossom algorithm); the edge weights encode the FIDE criteria.
  • 0 discrepancies against bbpPairings, FIDE's reference engine, across 10,000 simulated tournaments. Not FIDE-endorsed.
  • 252 tests, run in CI on Linux and macOS with Python 3.10 to 3.13.
  • Python
  • NetworkX
  • pytest
  • GitHub Actions
  • PyPI
Visit site ↗ Source code ↗

Caissify Tournament Manager (desktop)

Apr 2026 – Present

Founder & Lead Engineer (self-directed)

Offline-first desktop app for chess arbiters: Swiss and round-robin pairings, TRF16 import/export, tiebreaks, PDF sheets and one-click sync to the cloud.

  • Rust backend with SQLite, React 19 + TypeScript front end, English and Spanish.
  • Ships the Python pairing engine inside the app as a self-contained sidecar.
  • GitHub Actions builds signed installers for macOS (notarized), Windows and Linux; CI runs type checks, tests, cargo fmt and clippy.
  • Rust
  • Tauri 2
  • React 19
  • TypeScript
  • SQLite
  • Python
  • GitHub Actions
Visit site ↗

Pirakito: private, local-first finance app

Oct 2026 – Present

Personal project

End-to-end encrypted household finance app that works offline first.

  • Integer-only money, an immutable ledger corrected by reversals, and an offline outbox that never drops changes.
  • Passkey unlock with WebAuthn; data is stored encrypted in IndexedDB and synced through PocketBase.
  • About 780 tests: unit, property-based, Playwright end-to-end and upgrade tests, all in GitHub Actions CI.
  • TypeScript
  • Vue 3
  • PWA
  • IndexedDB
  • libsodium
  • WebAuthn
  • PocketBase
  • Playwright

lexisvar.me

Personal project

This site: a small Laravel CMS that renders my CV as a web page, an ATS-friendly page and a PDF from one data source, with an admin area, feature tests and a Docker deploy on Railway.

  • PHP
  • Laravel
  • Blade
  • dompdf
  • PHPUnit
  • Docker
  • Railway
Visit site ↗ Source code ↗

Experience

Jul 2024 – Present

Chess Coach

Sydney Academy of Chess

  • Teach group classes, private lessons and training squads for juniors and adults
  • Plan lessons and progressions, and prepare students for rated tournaments
  • This work shaped the tournament and coaching tools I built in Caissify
Feb 2022 – Jun 2024

Ruby on Rails Developer

Shore

  • Developed and maintained features in a Ruby on Rails SaaS platform
  • Wrote complex PostgreSQL queries and reports, and connected them to Vue.js front ends
  • Implemented Elasticsearch-backed search
  • Worked in sprints with Jira, pull-request code review and CI in an Agile team
Jan 2020 – Feb 2022

PHP Laravel Developer

Grupo Bien Pensado

  • Designed and built REST APIs in Laravel for several client projects, used by web and mobile apps
  • Modelled relational schemas and wrote efficient queries
  • Agreed API contracts with front-end and mobile developers
Jun 2017 – Mar 2019

PHP Analyst

HandyCommerce

  • Maintained and extended e-commerce products built on Laravel, WordPress/WooCommerce, Vue.js and Angular
  • Integrated Elasticsearch for product search
  • Delivered client features in a small development team
Jan 2015 – Nov 2017

Project Manager & Developer

Solvitio

Mar 2013 – Nov 2014

Linux Server Support

Factoria Digital

Mar 2012 – Mar 2013

PHP Developer

Grupo i33

Skills

Backend
  • Python
  • Django
  • Django REST Framework
  • Celery
  • Django Channels / WebSockets
  • REST API design
  • OpenAPI
Frontend
  • Vue 3
  • TypeScript
  • React
  • Pinia
  • Vite
  • Tailwind CSS
Mobile & Desktop
  • Flutter
  • Dart
  • Rust
  • Tauri
Data
  • PostgreSQL
  • Redis
  • SQLite
  • Elasticsearch
Cloud & DevOps
  • Docker
  • Railway
  • GitHub Actions
  • Sentry
  • AWS S3
  • Linux
AI-assisted development
  • Claude Code
  • Cursor
  • LLM APIs
Also experienced in
  • PHP
  • Laravel
  • Ruby
  • Ruby on Rails
  • MySQL

Education

Oct 2026

Bachelor of Systems Engineering

Corporación Universitaria Remington, Colombia · Ingeniero de Sistemas

Contact

Let's talk

I am open to backend and full-stack engineering roles in Sydney. I am happy to walk you through the Caissify code or the pairing engine. The quickest way to reach me is by email.

lexisvar@gmail.com