Aws

This is a cross-post. I wrote this up for the dev.to audience. For the full architecture, benchmarks, and SDK compatibility numbers, read the in-depth write-up here on the site: Introducing Floci. Floci’s ~24 ms startup is not one clever trick. It is four battle-tested open-source projects stacked on top of each other, each doing the job it does best: Netty for high-performance async I/O. Vert.x for the reactive, event-driven toolkit. Quarkus for the application framework and build-time optimization. GraalVM Mandrel to compile the whole thing to a native binary. Together they take startup from the 2 to 6 seconds a typical JVM app needs down to ~24 ms, and idle memory from a few hundred MiB down to ~13 MiB. The honest takeaway is that this speed is borrowed: years of production hardening in those libraries are what let Floci spend its own effort on the part that matters, AWS protocol fidelity across 45 services and 1,925 SDK compatibility tests (Java, Python, Node.js, Go, and Rust). ...

This is a cross-post. I wrote this up for the dev.to audience. For the full architecture, benchmarks, and SDK compatibility numbers, read the in-depth write-up here on the site: Introducing Floci. “Java” is not the answer people expect for a tool that has to feel instant. But the choice was made on constraints, not taste. Floci needs to cold start in milliseconds, idle in single-digit MiB, and ship as one small binary that drops cleanly into a CI pipeline. Java 25, compiled with Quarkus and GraalVM, hits all three: a ~24 ms cold start, ~13 MiB idle memory, and a single ~90 MB binary. Modern features like virtual threads let it juggle many AWS services concurrently without ceremony. ...

This is a cross-post. I wrote up the design philosophy behind Floci for the dev.to audience. For the full architecture, benchmarks, and SDK compatibility numbers, read the in-depth write-up here on the site: Introducing Floci. Most AWS emulators make you pick a side: fast-but-fake (shallow mocks that pass your unit tests but never catch real integration bugs) or heavy-but-faithful (a giant container that boots in seconds and eats hundreds of MiB). Floci refuses that tradeoff. ...

This is a cross-post. I wrote this up for the dev.to audience. For the full architecture, benchmarks, and SDK compatibility numbers, read the in-depth write-up here on the site: Introducing Floci. Persistence is exactly the kind of feature emulators love to lock behind a Pro tier. In Floci it is free, and it is configurable. You get four storage modes and you can set them globally or per service, so each service gets the durability versus speed trade-off that actually fits your workload: ...

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. ...