Build SNS topic access policies for cross-account and service publishing.
Last verified: May 2026
Output will appear here...The SNS Topic Policy Builder helps you create access policies for Amazon SNS topics with proper principal, action, and condition configurations. SNS topic policies control which AWS accounts, services, or endpoints can publish or subscribe to your topics. This tool provides a form-based interface for building these policies, handling the JSON syntax and ARN formats so you can focus on defining the access rules you need.
By default, only the topic owner can publish or subscribe. If you need other AWS accounts or services (like S3, CloudWatch, or EventBridge) to interact with your topic, you must add a resource-based policy granting them explicit permission.
Yes. SNS evaluates both the topic's resource-based policy and the caller's IAM policy. Access is granted if either policy allows it, unless there is an explicit deny. For cross-account access, both the topic policy and the caller's IAM policy must allow the action.
Your security team mandates that all SNS topics in production must restrict cross-service publishes to specific source ARNs. The builder generates a policy template for 'allow S3 bucket events' that includes a Condition block with aws:SourceArn matching only your 3 specific buckets. Without the tool, the team would have hand-crafted JSON (and one developer would forget the SourceArn condition, leaving the topic vulnerable). With the tool, all 40+ production topics get consistent locked-down policies in 2 hours.
The builder collects SNS-specific policy parameters (Effect, Principal, Action like sns:Publish/sns:Subscribe, Resource as topic ARN, Conditions like aws:SourceArn) and assembles them into a valid resource-based policy JSON. It pre-populates common patterns (allow S3 to publish, allow CloudWatch Alarms, etc.) so you can pick a template and customize rather than build from scratch.
When granting AWS services (S3, CloudWatch, EventBridge) publish access to your topic, use the aws:SourceArn condition to restrict which specific resource can trigger publishes. Without this, ANY S3 bucket in your account could publish to your topic — a vector for noisy-neighbor or accidental fan-out.
Cross-account SNS access requires BOTH the topic policy granting access AND an IAM policy in the consuming account allowing the principal to use the topic. Missing either side fails silently with 'AccessDenied' that's frustrating to debug. Always verify both sides when troubleshooting cross-account SNS.
Default SNS topic policies allow all subscribers to subscribe automatically. For sensitive topics (e.g., security incident notifications), explicitly restrict the sns:Subscribe action to specific principals. Otherwise, anyone with topic ARN visibility could subscribe and receive sensitive event data.
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