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This is a cross-post. I wrote a shorter, community-friendly intro to Floci for the dev.to audience. If you want the full architecture, benchmarks, and SDK compatibility numbers, read the in-depth write-up here on the site: Introducing Floci. The short pitch: LocalStack Community Edition started requiring auth tokens and moved features behind paid tiers in early 2026. Floci fills that gap, a free, open-source, MIT-licensed AWS emulator that starts in ~24ms, idles at ~13 MiB, runs on the same port 4566, and never asks for an account, token, or quota. ...

Floci is a suite of local cloud emulators that let you run AWS, Azure, and GCP services on your own machine, with no accounts, auth tokens, or usage limits. Every emulator is built with Quarkus, compiled to a native binary with GraalVM Mandrel, starts in ~24 ms, and idles around 13 MiB. Everything is MIT-licensed and free forever. The name comes from cirrocumulus floccus, a small, fluffy cloud formation. That’s the design goal: minimal, lightweight, and always free. ...

Local development against AWS services has always been painful. You either run real AWS (expensive, slow, requires an internet connection) or use an emulator. For years, LocalStack was the go-to choice, until they required auth tokens and locked down their community edition in early 2026. That gap is exactly what Floci fills. Key Numbers: Native Floci vs LocalStack Metric Native Floci LocalStack Advantage Startup Time ~24 ms ~3,300 ms 138× faster Idle Memory ~13 MiB ~143 MiB 91% less Lambda Latency 2 ms avg 10 ms avg 5× faster Lambda Throughput 289 req/s 120 req/s 2.4× faster Price Free Forever Auth Token Req. $0 / No Auth What Is Floci? Floci is a free, open-source local AWS service emulator written in Java using Quarkus and compiled to a native binary via GraalVM Mandrel. It runs as a single process on port 4566, the same port LocalStack uses, so switching requires zero changes to your existing code or tooling. ...

Workshop presented at PUCMM, November 2023. Co-presented with Freddy Peña. Overview In this workshop, we explored how the Java ecosystem has evolved to allow developers to build modern, highly interactive, and scalable web applications without the traditional complexity of managing separate frontend and backend stacks. The focus was on Vaadin Flow, a framework that enables building web UIs 100% in Java, running on the server side while automatically handling the synchronization with the browser. ...