Dev
Mock AWS ARN Generator
The mock AWS ARN generator produces realistic, properly formatted Amazon Resource Names you can drop straight into IAM policies, Terraform modules, CloudFormation templates, and API mocks without exposing real account IDs or live resource identifiers. ARNs follow the pattern arn:partition:service:region:account-id:resource, and every component must be structurally correct for tooling like aws iam simulate-policy or cfn-lint to accept it without errors. Getting the format wrong wastes debugging time, so having a ready source of valid fake ARNs speeds up early-stage policy authoring considerably. Developers routinely need placeholder ARNs when writing permission boundaries, building least-privilege policies for services like S3, Lambda, DynamoDB, SNS, SQS, and RDS, or scaffolding infrastructure-as-code before real resources exist. Using real ARNs from a production account in test configs or public documentation is a security risk: account IDs alone can narrow an attacker's reconnaissance. Fake ARNs that are structurally identical to real ones eliminate that risk entirely. This tool lets you pick a specific AWS service and generate a batch of ARNs in one click. Each output uses randomised but plausible account IDs, region codes, and resource names that match the naming conventions for that service. You can paste them directly into JSON policy documents, README examples, Postman mocks, or unit test fixtures. Beyond testing, mock ARNs are useful in developer-facing documentation, training materials, and onboarding runbooks where you want to show real-looking examples without leaking infrastructure details. Generating a fresh set for each document keeps examples varied and avoids readers assuming the shown values are authoritative.
How to Use
- Select the AWS service you need ARNs for using the Service dropdown (e.g., S3, Lambda, DynamoDB).
- Set the count field to the number of ARNs you want generated in one batch.
- Click Generate to produce a list of correctly formatted fake ARNs for that service.
- Copy individual ARNs or the full list and paste them into your policy JSON, Terraform variable file, or test fixture.
- Re-run with a different service selected to generate ARNs for a second service without mixing formats.
Use Cases
- •Populating IAM policy documents with S3 bucket ARNs before buckets exist
- •Unit-testing Lambda permission logic against fake execution role ARNs
- •Filling Terraform variable files with placeholder RDS and DynamoDB ARNs
- •Writing CloudFormation templates that reference SNS topic ARNs in dev
- •Creating realistic Postman mock responses that include resource ARNs
- •Generating ARN examples for internal AWS onboarding runbooks
- •Simulating IAM policies with aws iam simulate-policy using safe fake ARNs
- •Populating README documentation with SQS queue and IAM role ARN samples
Tips
- →Generate S3 ARNs separately from other services — S3 omits region and account-id, so mixing them in a policy array will look inconsistent.
- →When writing IAM resource arrays, generate one ARN per logical resource type to make your policy examples more realistic and easier to teach from.
- →Paste generated ARNs into cfn-lint or a JSON schema validator for your policy format before sharing — confirms structural correctness quickly.
- →For unit tests, store generated ARNs in a dedicated fixtures file and import them, rather than inlining them in each test, so swapping them out later is trivial.
- →Combine this generator with a mock account-ID list to simulate cross-account trust policies where the principal ARN must be from a different account than the resource ARN.
- →Avoid reusing the same fake ARN across multiple unrelated documents — regenerate fresh ones each time to prevent readers assuming a specific value is canonical.
FAQ
What is an AWS ARN and what format does it use?
An Amazon Resource Name (ARN) uniquely identifies every AWS resource. The format is arn:partition:service:region:account-id:resource-type/resource-id. Partition is usually 'aws'; region and account-id can be empty for global services like IAM. Every IAM policy, CloudFormation cross-stack reference, and SDK call that targets a specific resource requires an ARN in this exact structure.
Are the generated ARNs safe to use in public documentation?
Yes. Account IDs and resource names are randomly generated and do not correspond to any real AWS account or resource. Unlike copying ARNs from a real environment, these carry no sensitive infrastructure information, making them safe for public READMEs, blog posts, training slides, and open-source repositories.
Will fake ARNs work with aws iam simulate-policy?
Yes, for policy simulation purposes. The simulate-policy API validates permission logic against the ARN format, not against whether the resource actually exists. Structurally correct fake ARNs let you test Allow/Deny outcomes for S3, Lambda, DynamoDB, and other services without needing live resources in your account.
Do different AWS services have different ARN formats?
Yes. S3 bucket ARNs omit region and account-id (arn:aws:s3:::bucket-name), while Lambda function ARNs include both. IAM ARNs use a path segment before the resource name. This generator applies the correct format pattern for the service you select, so the output is structurally valid for that service.
Can I use these ARNs in Terraform or CloudFormation without errors?
For static analysis and linting, yes. Tools like cfn-lint and terraform validate check format validity, and correctly structured fake ARNs will pass. At apply/deploy time, AWS will reject references to non-existent resources, but that is expected — these are placeholders for pre-production and documentation use, not for live deployments.
How many ARNs should I generate at once?
For unit test fixtures, generate at least 5-10 so your tests cover varied resource identifiers rather than a single hardcoded value. For documentation examples, 2-3 per service is usually enough. Policy stress-testing with many conditions may benefit from generating 20+ ARNs to populate resource arrays in IAM policy statements.
What AWS services are supported by this generator?
The generator covers commonly used services including S3, Lambda, IAM, DynamoDB, SNS, SQS, EC2, and RDS. Each service uses its correct ARN structure, region handling, and resource naming convention so the output matches what you'd see in a real AWS console or CLI response for that service.
Is there a risk of accidentally generating an ARN that matches a real resource?
The probability is astronomically low. AWS account IDs are 12-digit numbers drawn from a huge space, and resource names are randomised strings. The chance of a collision with a real resource in your account — or anyone's — is effectively zero. Treat generated ARNs as safe placeholders with no real-world counterpart.