Public S3/Resource Bucket Policy Detector scans a pasted resource-based policy (an S3 bucket policy, or any other resource policy that uses a Principal element) for Allow statements that grant access to "*" — the special principal value that means "any AWS principal, or literally anyone, depending on context," i.e. the internet at large. This is one of the single most common and most dangerous S3 misconfigurations: a bucket policy statement with "Principal": "*" and no restricting condition makes the affected actions available to anyone who finds the bucket, not just your own account.
Each match is classified by risk: high when the public statement has no Condition block at all (fully public, no exceptions), and medium when a Condition block is present, since a condition narrows who "*" resolves to in practice — but this tool does not attempt to judge whether the specific condition you wrote is actually restrictive. A condition that requires aws:SourceIp = 0.0.0.0/0, for example, restricts nothing, and this tool has no way to tell the difference between that and a genuinely narrow condition; it only checks whether a Condition key is present at all.
This is a heuristic check against one known pattern, not a full bucket-exposure audit — it has no visibility into S3 Block Public Access settings, bucket ACLs, cross-account grants outside the policy JSON, or anything else that determines real-world accessibility. Treat a clean result as "no public-principal Allow statement in the JSON you pasted," not as "this bucket is private."