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. 23 services, 1,680 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 13 runtimes, RDS runs real PostgreSQL/MySQL/MariaDB, ElastiCache runs real Redis/Valkey.
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 v2, Bedrock, Bedrock Runtime.

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.