Lucas Aguiar

Deep expertise

Go· 6+ yearsPython / Django· 5+ yearsPostgreSQL· query optimization, schema design, billions of recordsGitSystem Design· ETL pipelines, data aggregation, API designQuery Optimization

Production experience

RedisDockerCI/CD (GitHub Actions)Clean Architecture· DDD, dependency injectionTDD / TFDMachine Learning· TensorFlow, CNNsReactTailwind CSSRubyPHPGCP· PubSub, Cloud SQL, Cloud StorageAWSCloudflareAnsibleTerraformKubernetesRabbitMQFlutterDokployInfrastructure / DevOps
GitHubLinkedIn

Experience

Toggl

Senior Backend Engineer

Dec 2019 – Present · 6+ yr

Core member of the Reports / Data Visualization team, responsible for analytics infrastructure serving 2 billion time entries across Toggl's product suite.

ETL & Analytics Pipeline

Before this system, large users couldn't even pull monthly data — most requests just timed out. Designed and shipped an ETL pipeline that made "all-time" reports possible for the first time. Worst-case response dropped to under 3 seconds.

DSL Report Engine

A configuration-driven engine where adding a new report means writing a handler and a service — nothing else changes. Three products (Track, Work, Focus) run on it today, fully decoupled. Onboarding a second product took days, not months.

Historical Billable Rates

Temporal billing across 4 hierarchy levels (Workspace → Workspace User → Project → Project User) with flexible effective dates. ~200M time entries affected. Users pay employees based on this data, so there was zero margin for error.

Calendar Integration

Sync with Google and Outlook Calendar — calendar events show up as time entries.

Reports V2 → V3 Migration

Replaced the legacy reports infrastructure with v3 internals while keeping every endpoint alive. Clients saw zero breaking changes thanks to an internal abstraction layer.

Architectural contributions adopted org-wide:

  • Proposed and implemented the fake package pattern for test data generation
  • Created Query API for backend integration testing
  • Introduced Database interface pattern for dependency inversion

CatruTech

Founder & Backend Engineer

Apr 2021 – Present

Building products from zero to production — architecture, development, and infrastructure. Focus on creating self-sustaining systems that require minimal maintenance.

Vodsafe — Video On Demand Platform

Distributed video streaming platform for security monitoring: live streaming, historical playback, multi-camera management. Currently serving 84+ cameras. Master server (Django) + scalable Stream servers (Go + OvenMediaEngine). Frontend built with React and Tailwind CSS. Self-provisioned bare-metal infrastructure via Ansible.

Ágrafo — Legal Document Automation

Document generation platform for law firms. Built template engine that compiles legal documents from configurable models. Frontend built with React and Tailwind CSS. Reduced document preparation time by 78% (90 min → 25 min). Zero maintenance required since launch.

Havenly

ETL Data Engineer (Contractor)

Aug 2019 – Nov 2019 · 4 mo

Migrated legacy PHP ETL system to Python, improving maintainability and performance.

Justiça Fácil

Lead Engineer

Dec 2018 – Aug 2019 · 9 mo

Led technical and managerial decisions for Processamento, an ETL system processing official court orders from Brazilian tribunals. Implemented a Deep Learning solution (TensorFlow, Convolutional Neural Networks) to automatically extract legal publications from official gazettes. Replaced a team of 20+ manual processors, recouping 8 years of team costs within 6 months. Focused on team development, delivery consistency, and process stabilization.

Back-end Developer

Sep 2016 – Dec 2018 · 2 yr 4 mo

Built Andamentos, a Python web crawler extracting lawsuit data from all Brazilian courthouses — millions of requests daily. Scaled through database indexing, profiling, Docker optimization, and proxy management. Later initiated Processamento, a microservices-based ETL system for court PDF processing.

Okapi

Freelancer Back-end Developer

2017 – 2019

Built an API from scratch with automated infrastructure provisioning (Ansible), full test coverage, and a web crawler for large-scale database scraping using SOCKS5 proxies.

Novo Nordisk

Trainee

Nov 2015 – Nov 2016 · 1 yr 1 mo

Fully responsible for maintaining a SCADA system, solving non-conformities and other legal tasks, dealing with instrumentation and automation. The system maintained was responsible for releasing the product batch documentation.

Intern

Sep 2014 – Nov 2015 · 1 yr 3 mo

Worked with validated systems, instrumentation, and industrial automation in a GMP environment.

Publications

Education

Systems Engineering

Bachelor's degree

Unimontes — Universidade Estadual de Montes Claros