Floci is a free, open-source local AWS emulator for development, testing and CI. It runs on your machine and answers AWS-style API calls at http://localhost:4566, so the AWS CLI, the SDKs, Terraform and Testcontainers can talk to it with dummy credentials and no AWS account. It is made by the floci-io organisation on GitHub (the project started under its creator's account, hectorvent) and has sister emulators for Azure, Google Cloud and Oracle Cloud.
Why people are looking at it: on 23 March 2026 LocalStack retired its free Community edition. Its single Docker image now refuses to start without a LOCALSTACK_AUTH_TOKEN tied to a registered account, the free Hobby plan is for non-commercial use only, commercial plans start at $39 a month, and the archived Community code no longer gets security updates. Floci pitches itself as a drop-in replacement: no account, no token, the same port, and it translates many LocalStack environment variables. Moving over is mostly a matter of swapping the image name.
What it does well, by its own numbers: it is built on Quarkus and compiled to a native binary. The project advertises a start-up of about 24 ms, about 13 MiB of memory at idle and an image of about 90 MB (against about 1 GB for LocalStack), plus a 100% pass rate on 1,925 SDK compatibility tests. Services such as RDS, ElastiCache, EKS and ECS run in real Docker containers rather than in-process mocks, and the core ones (S3, SQS, SNS, DynamoDB, Lambda, IAM, KMS…) are covered. A hands-on check reported in the DEV article measured start-up closer to 130 ms, so treat the figures as best-case.
Try it: run floci start then eval $(floci env) with the Floci CLI, or put the floci/floci:latest image on port 4566 in your Docker Compose file and run docker compose up. Stable releases ship on the 15th and the last day of each month, with nightly builds in between.
Licence and limits: MIT. The repository has about 31,000 stars and 3,400 forks; it reached up to about 1,090 new stars in a day on GitHub trending between 3 and 6 November, and earlier Hacker News posts got 292 points (March) and 220 points (September). It is younger than LocalStack and has less breadth and edge-case coverage; Hacker News commenters noted that LocalStack works closely with AWS and doubted a community project can keep up with every service change. Check that the services you rely on are covered before switching a whole team.
