Fake AWS server for tests

fakecloud is a free, open-source fake AWS server for integration tests. Single binary, port 4566, any AWS SDK in any language. No account, no auth token, no paid tier.

Need a fake AWS server to point your tests at? That's what fakecloud is.

curl -fsSL https://raw.githubusercontent.com/faiscadev/fakecloud/main/install.sh | bash
fakecloud

Listens on http://localhost:4566. Any AWS SDK in any language points at it and it responds like AWS.

What "fake AWS server" means here

Real HTTP server, not an in-process mock. Your Go / Java / Kotlin / Node / Rust / PHP / Python code uses the regular AWS SDK with endpoint_url set to http://localhost:4566.
Speaks the AWS wire protocol at 100% conformance per implemented service. 33 services, 2,422 operations, validated against AWS's own Smithy models on every commit (59,000+ generated test variants).
Real execution for stateful services: Lambda runs your function code in Docker containers across 23 runtimes, RDS runs real PostgreSQL/MySQL/MariaDB/Oracle/SQL Server/Db2, ElastiCache runs real Redis/Valkey/Memcached.
Real cross-service wiring: S3 -> Lambda, SQS -> Lambda, SNS fan-out, EventBridge -> Step Functions, and 15+ more integrations execute end-to-end, not as stubs.
Free, open-source, AGPL-3.0. No account, no auth token, no paid tier.

Services covered

S3, SQS, SNS, DynamoDB, Lambda, IAM, STS, KMS, Secrets Manager, SSM, CloudWatch Logs, CloudFormation, EventBridge, EventBridge Scheduler, SES (v2 + v1 inbound), Cognito User Pools, Kinesis, RDS, ElastiCache, Step Functions, API Gateway v1 (REST), API Gateway v2 (HTTP), Bedrock, Bedrock Runtime, ECR, ECS, Elastic Load Balancing v2, CloudFront, Route 53, ACM, Application Auto Scaling, WAF v2, Athena.

Full matrix: fakecloud.dev/docs/services.

Minimal example

Node.js

process.env.AWS_ENDPOINT_URL = "http://localhost:4566";
process.env.AWS_ACCESS_KEY_ID = "test";
process.env.AWS_SECRET_ACCESS_KEY = "test";
process.env.AWS_REGION = "us-east-1";

import { S3Client, CreateBucketCommand } from "@aws-sdk/client-s3";
const s3 = new S3Client({});
await s3.send(new CreateBucketCommand({ Bucket: "hello" }));

Python

import boto3
s3 = boto3.client("s3",
    endpoint_url="http://localhost:4566",
    aws_access_key_id="test",
    aws_secret_access_key="test",
    region_name="us-east-1")
s3.create_bucket(Bucket="hello")

Go

cfg, _ := config.LoadDefaultConfig(ctx,
    config.WithRegion("us-east-1"),
    config.WithCredentialsProvider(credentials.NewStaticCredentialsProvider("test", "test", "")),
    config.WithEndpointResolverWithOptions(aws.EndpointResolverWithOptionsFunc(
        func(service, region string, opts ...interface{}) (aws.Endpoint, error) {
            return aws.Endpoint{URL: "http://localhost:4566"}, nil
        },
    )),
)
s3 := s3.NewFromConfig(cfg, func(o *s3.Options) { o.UsePathStyle = true })

AWS CLI

aws --endpoint-url http://localhost:4566 s3 mb s3://hello

How it differs from in-process mocks

Mocks (Moto, aws-sdk-client-mock, aws-sdk-mock) intercept SDK calls inside your test process and return fabricated responses. That's useful for tight unit tests but it does not execute cross-service wiring, does not run Lambda code, and is language-locked to the library's ecosystem.

A fake AWS server on localhost is language-agnostic (any SDK works), runs real cross-service flows, and executes Lambda code in real containers. If your tests ask "does my whole system actually work end-to-end," the server is the right tool.

Install options

Binary: curl -fsSL https://raw.githubusercontent.com/faiscadev/fakecloud/main/install.sh | bash
Docker: docker run --rm -p 4566:4566 ghcr.io/faiscadev/fakecloud
Cargo: cargo install fakecloud
Docker Compose and source builds: docs

Test-assertion SDKs

fakecloud ships introspection endpoints so your tests can assert on side effects (emails sent, messages published, Lambdas invoked) without writing raw HTTP:

import { FakeCloud } from "fakecloud";
const fc = new FakeCloud();

const { emails } = await fc.ses.getEmails();
expect(emails).toHaveLength(1);

await fc.reset();

SDKs for TypeScript, Python, Go, PHP, Java, Rust. Docs: fakecloud.dev/docs/sdks.