Test Lambda locally

Run AWS Lambda locally with real runtimes and real event triggers. 13 Lambda runtimes, real S3/SQS/SNS/EventBridge triggers, no account required.

Want to run AWS Lambda locally? Use fakecloud.

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

What you get

All 13 AWS Lambda runtimes — Node 18/20/22, Python 3.11/3.12/3.13, Java 17/21, .NET 8, Ruby 3.3/3.4, custom (provided.al2, provided.al2023).
Real code execution. fakecloud pulls the AWS Lambda runtime container and runs your handler. Not a stub, not a simulated response.
Real event triggers. S3 -> Lambda, SQS -> Lambda, SNS -> Lambda, EventBridge -> Lambda, DynamoDB Streams -> Lambda, API Gateway v2 -> Lambda. All wired end-to-end.
Real event source mappings. fakecloud polls SQS/Kinesis, batches events, invokes your Lambda, handles success/failure/DLQ the way AWS does.
CloudWatch Logs. Your function's stdout captured and queryable via aws logs tail.
No account, no auth token, no paid tier.

Quick deploy + invoke

# Node.js example
cat > index.js <<'EOF'
exports.handler = async (event) => ({ ok: true, event });
EOF
zip fn.zip index.js

aws --endpoint-url http://localhost:4566 iam create-role \
  --role-name lambda-role \
  --assume-role-policy-document '{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Service":"lambda.amazonaws.com"},"Action":"sts:AssumeRole"}]}'

aws --endpoint-url http://localhost:4566 lambda create-function \
  --function-name hello \
  --runtime nodejs20.x \
  --role arn:aws:iam::000000000000:role/lambda-role \
  --handler index.handler \
  --zip-file fileb://fn.zip

aws --endpoint-url http://localhost:4566 lambda invoke \
  --function-name hello \
  --payload '{"hi":true}' \
  --cli-binary-format raw-in-base64-out \
  out.json

cat out.json

How it compares

Tool	Runs function code	Multi-runtime	Cross-service triggers	Language	Free
fakecloud	Yes (Docker)	13 runtimes	Yes (S3, SQS, SNS, EventBridge, DynamoDB Streams, API GW v2)	Any	Yes
SAM Local	Yes (Docker)	All AWS runtimes	Partial (synthetic events only)	Any	Yes
LocalStack Community (post-Mar 2026)	Yes (Docker, auth required)	All	Yes	Any	No (auth token required)
serverless-offline	Yes (in-process)	Node only	API Gateway only	Node	Yes
Moto	No	N/A	No	Python	Yes

Full tutorial

Step-by-step guide with S3, SQS, EventBridge triggers and test-assertion examples: How to test Lambda locally.

Install

Binary: curl -fsSL https://raw.githubusercontent.com/faiscadev/fakecloud/main/install.sh | bash
Docker: docker run --rm -p 4566:4566 -v /var/run/docker.sock:/var/run/docker.sock ghcr.io/faiscadev/fakecloud
Cargo: cargo install fakecloud