Overview
MildStack is a lightweight, open-source, local-first AWS emulator. No Docker required. Start emulating S3, DynamoDB, and SQS in under 200ms.
What is MildStack?
MildStack is a high-performance, local-first AWS emulator designed to streamline your cloud development workflow. Unlike heavyweight alternatives that require Docker and significant system resources, MildStack is built in Go for maximum efficiency and speed.
Stop waiting for containers to spin up. Start building instantly with a local cloud that runs natively on your machine.
Fast by default
No Docker required. The MildStack runtime starts in approximately 200ms and uses minimal CPU and RAM.
Why MildStack?
| Feature | MildStack | LocalStack (Free) |
|---|---|---|
| Startup time | ~200ms | 30–60s |
| Docker required | No | Yes |
| Memory usage | ~20 MB | ~500 MB+ |
| Desktop GUI | ✅ Built-in | ❌ |
| S3, DynamoDB, SQS | ✅ | ✅ |
| Cost | Free & Open Source | Free (limited) |
The Ecosystem
MildStack is organized into three parts that work together:
Core Runtime
The Go engine that emulates AWS-compatible APIs with instance-scoped persistent state.
MildStack CLI
A modern terminal-based control center to manage local instances, view logs, and monitor services.
Desktop App
An Electron-powered visual console to browse S3 buckets, query DynamoDB tables, and inspect SQS queues.
Supported Services
MildStack currently focuses on the services that matter most in local development:
| Service | Status | Highlights |
|---|---|---|
| Amazon S3 | ✅ Active | Buckets, objects, multipart uploads, versioning, object lock, tagging, ACLs |
| Amazon DynamoDB | ✅ Active | Tables, items, GSI/LSI, query/scan, batch and transaction operations |
| Amazon SQS | ✅ Active | Standard and FIFO queues, DLQ redrive, message move tasks, visibility timeout |
Coming Soon
- Amazon SNS — Topic publishing and subscriptions
- AWS Lambda — Local serverless function execution
- Amazon EventBridge — Event-driven architecture simulation
How It Works
The architecture is intentionally simple:
- The Core Runtime owns all AWS emulation logic and persistent state.
- The CLI and Desktop App communicate with the runtime over HTTP — they never embed emulation logic.
- Your application connects to the local endpoint using standard AWS SDKs — just change the endpoint URL.
┌─────────────┐ ┌──────────────┐ ┌───────────────────┐
│ Your App │────▶│ MildStack │────▶│ Instance State │
│ (AWS SDK) │ │ Core (Go) │ │ (~/.mildstack/) │
└─────────────┘ └──────────────┘ └───────────────────┘
▲ ▲
│ │
┌──────┴──────┐ ┌──────┴──────┐
│ Desktop │ │ CLI │
│ App │ │ │
└─────────────┘ └─────────────┘