MildStack: Free Open Source LocalStack Alternative

Get MildStack running in under a minute. Start a local AWS environment, create an S3 bucket, and send your first SQS message.

Start the Runtime

Launch a MildStack instance with a single command:

mildstack start

By default, the runtime starts on port 4566. You can specify a different port:

mildstack start 8080

To start the instance in the background (detached mode):

mildstack start --detach

Ready in milliseconds

MildStack starts in approximately 200ms. No containers, no waiting.

Configure Your AWS SDK

Point your AWS SDK to the local MildStack endpoint. MildStack ignores credentials, so you can use any dummy values:

import { S3Client } from "@aws-sdk/client-s3";

const client = new S3Client({
  region: "us-east-1",
  endpoint: "http://localhost:4566",
  credentials: {
    accessKeyId: "test",
    secretAccessKey: "test",
  },
  forcePathStyle: true,
});

Use the AWS CLI

You can also use the standard AWS CLI with MildStack:

# Configure a local profile
aws configure set aws_access_key_id test --profile mildstack
aws configure set aws_secret_access_key test --profile mildstack
aws configure set region us-east-1 --profile mildstack

# Create an S3 bucket
aws s3 mb s3://my-bucket --endpoint-url http://localhost:4566 --profile mildstack

# List buckets
aws s3 ls --endpoint-url http://localhost:4566 --profile mildstack

# Upload a file
aws s3 cp ./myfile.txt s3://my-bucket/ --endpoint-url http://localhost:4566 --profile mildstack

Try DynamoDB

# Create a table
aws dynamodb create-table \
  --table-name Users \
  --attribute-definitions AttributeName=id,AttributeType=S \
  --key-schema AttributeName=id,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST \
  --endpoint-url http://localhost:4566 \
  --profile mildstack

# Put an item
aws dynamodb put-item \
  --table-name Users \
  --item '{"id": {"S": "user-1"}, "name": {"S": "Alice"}}' \
  --endpoint-url http://localhost:4566 \
  --profile mildstack

Try SQS

# Create a queue
aws sqs create-queue \
  --queue-name my-queue \
  --endpoint-url http://localhost:4566 \
  --profile mildstack

# Send a message
aws sqs send-message \
  --queue-url http://localhost:4566/000000000000/my-queue \
  --message-body "Hello from MildStack!" \
  --endpoint-url http://localhost:4566 \
  --profile mildstack

# Receive messages
aws sqs receive-message \
  --queue-url http://localhost:4566/000000000000/my-queue \
  --endpoint-url http://localhost:4566 \
  --profile mildstack

Manage Instances

Use the CLI to check on your running instances:

# List all instances
mildstack instances

# Show instance status (with JSON output)
mildstack instances --json

# Stop a specific instance
mildstack stop 4566

# Stop all running instances
mildstack stop --all

# Delete an instance and its data
mildstack delete 4566