What is the difference between S3 bucket policies and IAM policies?

IAM policies are attached to users, groups, or roles and control what actions those identities can perform. S3 bucket policies are attached to the bucket itself and control who can access that bucket. Both can grant or deny access; the effective permissions are the union of both, subject to explicit denies.

Can I use this to block public access to my bucket?

Yes, you can build a policy that explicitly denies access from principals outside your AWS account. However, for comprehensive public access prevention, you should also enable S3 Block Public Access settings at the bucket or account level.

Does this tool support S3 Access Points?

The builder focuses on standard bucket policies. S3 Access Points use a similar policy syntax but with different ARN formats. You can adapt the generated policy for access points by modifying the resource ARN.

AWS S3 Bucket Policy Builder

IAM & SecurityAWS

Visual builder for S3 bucket policies with principal, action, and condition support.

S3 Bucket Policy Configuration

Bucket Name

Statement 1

SID (optional)

Effect

Principal

Actions (comma-separated)

Resources (comma-separated, leave empty for bucket/*)

Condition Operator

Condition Key

Condition Value

Generated S3 Bucket Policy

Output will appear here...

About This Tool

The S3 Bucket Policy Builder provides a guided interface for constructing S3 bucket policies with proper principal, action, resource, and condition support. S3 bucket policies use the same IAM policy language but apply at the bucket level, and getting the JSON syntax right with the correct ARN patterns and condition keys can be error-prone. This tool walks you through each policy statement, validates your inputs, and generates correctly formatted JSON that you can apply directly to your S3 bucket.

When to Use This Tool

•Build a bucket policy to grant cross-account access to specific IAM roles while denying public access.
•Create a policy that enforces server-side encryption by denying PutObject requests without encryption headers.
•Configure a policy to restrict access to specific VPC endpoints or IP address ranges using condition keys.
•Generate a policy that allows CloudFront Origin Access Identity (OAI) or Origin Access Control (OAC) to read objects from a private bucket.

Frequently Asked Questions

What is the difference between S3 bucket policies and IAM policies?: IAM policies are attached to users, groups, or roles and control what actions those identities can perform. S3 bucket policies are attached to the bucket itself and control who can access that bucket. Both can grant or deny access; the effective permissions are the union of both, subject to explicit denies.
Can I use this to block public access to my bucket?: Yes, you can build a policy that explicitly denies access from principals outside your AWS account. However, for comprehensive public access prevention, you should also enable S3 Block Public Access settings at the bucket or account level.
Does this tool support S3 Access Points?: The builder focuses on standard bucket policies. S3 Access Points use a similar policy syntax but with different ARN formats. You can adapt the generated policy for access points by modifying the resource ARN.

Related Learning Guides

S3 Storage Classes Explained24 min read
AWS IAM Best Practices25 min read

Disclaimer: This tool runs entirely in your browser. No data is sent to our servers. Always verify outputs before using them in production. AWS, Azure, and GCP are trademarks of their respective owners.