Lucas Frederico

Senior backend engineer. 10 years on the JVM, building real-time systems with sub-50ms hot paths and recovery-under-60s SLOs.

Concurrent users on a single JVM shard

ms p95 hot-path latency

years of recovery-under-60s SLO

years on the JVM

GitHub LinkedIn s0urce_ Email

About

Senior backend on the JVM, for ten years.

Java backend engineer with a decade of production work. Five years on a real-time JVM platform sustaining 1,500 concurrent users on a single shard, with sub-50ms p95 on the hot path and a recovery-under-60s SLO held across 5 years.

Senior backend engineer on a 3-to-5-person team shipping that platform live: new features, performance work, cross-shard state on Redis, JVM tuning, audit-trailed idempotent operations. Before that, five years shipping enterprise Java/Angular systems for Kinross Gold, Grendene, and Olfar.

In parallel, I ship public OSS that anonymizes the patterns I run in production: fanloop (real-time fan-out, K8s + ArgoCD + Terraform end-to-end), tickloop (real-time JVM toolkit, Spring Boot 4 starter, JMH), pgcraft (Postgres TUI in Go), slow-query-watcher, pg_table_bloat.

Spring Boot 3 / Java 21+ in production, plus a Spring Boot 4 starter shipped via OSS
Cross-replica state via Redis pub/sub and distributed locks, no sticky sessions
Observability discipline: Grafana SLI/SLO dashboards, full audit trails, idempotent operations
Kubernetes + Helm + Kustomize + ArgoCD + Terraform end-to-end, demonstrated in fanloop
Postgres at the deep end: pgrx extension shipped, lazygit-style TUI shipped, slow-query observability

Certified

AWS Cloud Practitioner

Foundational · Amazon Web Services

// what I optimize for

throughput: "main-thread safe",

consistency: "network-wide",

recovery: "< 60s on incident",

audit: "every coin movement logged"

Open source

Three projects I'd put on a résumé.

fanloop v0.1.0 · MIT

Self-hostable real-time fan-out gateway. Spring Boot + Redis pub/sub backplane for cross-replica delivery with no sticky sessions. Helm chart, Kustomize overlays, ArgoCD app-of-apps with kube-prometheus-stack and a committed Grafana dashboard. Terraform module provisions the AWS platform (VPC, EKS, ElastiCache, ArgoCD bootstrap). CI deploys the full stack to a kind cluster and runs a cross-replica smoke test.

Java 25 / Spring BootKubernetes + ArgoCDTerraform

Real-time fan-out · K8s + GitOps end-to-end · CI on kind

github.com/lucasfrederico/fanloop

tickloop v0.2.1 · MIT

Real-time JVM toolkit in Java 21. Tick-based scheduler with main-thread safety guarantees, MPSC backpressure queues with four overflow modes, percentile histograms (p50/p95/p99), multi-rate TickGroup, virtual-thread offload pool. Includes a Spring Boot 4 starter and a JMH benchmark module. Anonymized extraction of patterns I ran in production for five years.

Java 21MPSC queuesJMH

Real-time JVM toolkit · 53 tests · CI matrix Java 21+23 · Linux + macOS

github.com/lucasfrederico/tickloop

pgcraft v0.1.0 · MIT

lazygit-style TUI for PostgreSQL. Schema browser, SQL editor, EXPLAIN view, pg_stat_user_tables and pg_stat_activity views, live filter. Postgres-only by design. Public Docker image on GHCR, multi-arch (amd64 + arm64), CI green on Linux and macOS.

GoBubble TeaPostgres internals

Postgres TUI · multi-arch Docker · keyboard-driven

github.com/lucasfrederico/pgcraft

Also shipped:

slow-query-watcher — Spring Boot 3 and 4 starter that auto-logs slow JDBC queries with full context (SQL, parameters, caller stack, transaction id). Drop the dep, set a threshold, done. JavaSpring Boot
pg_table_bloat — PostgreSQL extension in Rust (pgrx 0.13) that estimates table bloat from pg_class and pg_stats without pgstattuple. CI matrix Postgres 14 to 17. RustpgrxPostgres
django-multi-tenant-demo — Reference implementation of multi-tenant Django with queryset-filter isolation, audit triggers via signals + thread-local, JWT auth. PythonDjango

Production work

Backend on a live multiplayer platform.

Backend services on the LoverCraft real-time platform (Minecraft network, 1,500 concurrent users on a single JVM shard), shipped as part of a 3-to-5-person team. Full case studies, screenshots, and the rest of the LoverCraft work live at /minecraft →

LFAuctionHouse — Cross-server marketplace, rewritten from 2,800 lines of legacy JS into a clean Java system, and the foundation for two pieces of network-wide infrastructure.
PaperCustom ORMRedis
LFSkyBlockCore — The core gameplay system powering the network's SkyBlock gamemode: world-per-island, real-time cross-server sync, and a full plugin ecosystem on top.
PurpurNMSSlimeWorldManager
LFSBMines — Private mine system with custom mobs, animated 3D models, live block regeneration, and per-player stat tracking, fully integrated into the SkyBlock core.
PaperModelEngineMythicMobs

Enterprise experience

Five years of enterprise Java. Five of plugins.

LoverCraft LLC · Senior Backend Engineer · Freelance

Mar 2021 - Present·Remote

Senior backend engineer on a 3-to-5-person team running a US-based real-time JVM platform that sustains up to 1,500 concurrent users on a single shard, with sub-50ms p95 on the hot path and a recovery-under-60s production SLO held across 5 years. Worked across bug fixes, new features, and architecture: cross-shard state via Redis pub/sub, idempotent operations with full audit trails, JVM tuning, declarative infra (Ansible + Docker + Vagrant), CI/CD on GitHub Actions and GitLab, Grafana SLI/SLO dashboards. Domain: live multiplayer platform (Minecraft network) with 30+ network-wide services.

Stack: Java · Spring Boot · Spigot/Paper/Purpur · NMS · MySQL · MariaDB · MongoDB · Redis · Docker · Ansible · Vagrant · GitHub Actions · GitLab CI · Grafana · SonarQube

Senior Sistemas · FullStack Developer II · Software Factory

Apr 2021 - Feb 2024·Blumenau, Brazil

Full-stack development for major enterprise clients. Tech leadership on a fixed team, rotating into other squads as needed for surge work and senior technical decisions.

Kinross Gold (international gold mining): Third-Party Management system with HCM/ERP integration; monthly billing controls; Budget Management system for corporate budget oversight
Olfar: Lab Management system (sample tracking, label printing)
Grendene: Workforce Allocation system
Also: Flutter mobile applications.

Stack: Java · Spring Boot · Angular · Flutter · Docker · Oracle · MySQL · SQL Server · Maven · GitLab CI/CD · SonarQube · JIRA