Lucas Aguiar
Deep expertise
Solid
Basic
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). 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. 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 — a task previously done manually by a dedicated team. The system recovered 8 years of backlog in 6 months, eliminating the need for manual processing entirely. 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
Monitoring the Stator Current in Induction Machines for Possible Fault Detection: A Fuzzy/Bayesian Approach for the Problem of Time Series Multiple Change Point Detection
Sociedade Brasileira de Pesquisa Operacional · 2016
Fault detection in dynamic systems by a Fuzzy/Bayesian network formulation
Applied Soft Computing · 2014
Detecção de múltiplos pontos de mudança em séries temporais através de uma abordagem Fuzzy/Bayesiana
Simpósio Brasileiro de Pesquisa Operacional · 2013
Detecção de falhas em sistemas dinâmicos via uma formulação de rede Fuzzy/Bayesiana: Estudo de caso em uma Máquina de Indução
CBA · 2012
Education
Systems Engineering
Unimontes — Universidade Estadual de Montes Claros
Bachelor's degree