S3 is one of the few AWS services whose ARNs break the usual pattern. Every other resource ARN in this tool family carries a region and an account id between its colons — but S3 bucket names are globally unique across the whole of AWS, so a bucket ARN never needs to say which region or account owns it; AWS resolves that by looking the bucket up. The result is an ARN with two conspicuously empty fields: arn:aws:s3:::my-bucket, four colons in a row where other services would have real values. S3 ARN Generator builds this exact shape from a bucket name and an optional object key, so you never have to remember which fields to leave blank or second-guess whether a region belongs in there.
The form has exactly two meaningful inputs: a bucket name, and an optional object key (path). Leave the key blank and you get the bucket-level ARN used for actions like s3:ListBucket, s3:GetBucketPolicy, or s3:PutBucketVersioning in an IAM policy’s Resource field. Fill in a key — a single filename, or a deep path like logs/2026/08/20.log — and the object appended after a slash, giving you the object-level ARN needed for s3:GetObject, s3:PutObject, s3:DeleteObject and similar. Because most real IAM policies for S3 buckets need both the bucket ARN and an object-pattern ARN together (commonly arn:aws:s3:::my-bucket plus arn:aws:s3:::my-bucket/*), the tool makes it fast to generate both variants back to back from the same bucket name.
Region and account fields are deliberately absent from the form rather than shown disabled with placeholder text — the info banner explains why up front, so the empty fields in the resulting ARN read as correct rather than like something is missing. This is one of the more common points of confusion when people hand-build S3 ARNs for the first time: it looks incomplete next to a Lambda or DynamoDB ARN, but four colons with nothing between the third and fifth is exactly what AWS expects.
The object key field accepts anything a real S3 key can contain, including slashes (S3 has no real folder hierarchy — a key like a/b/c.txt is one flat object name that consoles render as nested folders) and wildcard characters such as *, which are valid and common in IAM policy resource patterns like my-bucket/uploads/*. Nothing is escaped or rewritten; what you type after the bucket name is what appears after the slash in the final ARN.
Bucket names get a light advisory check — uppercase letters and underscores are flagged, since virtual-hosted-style S3 bucket names are supposed to be lowercase with hyphens or dots — but this is a warning, not a hard stop, because the resulting ARN is still syntactically buildable and you may be intentionally working with a legacy or unusual name. After building, the ARN is run through the same structural validator used by every other tool in this family, checking partition, service, and confirming the region and account fields really are empty as expected for S3.
Once built, the ARN sits in a copy-ready box with a one-click Copy button, plus a Load sample button that fills in a realistic bucket and key so you can see both the bucket-only and bucket+object shapes immediately, and a Clear button to start over. Everything runs client-side in your browser — nothing about your bucket name or key ever leaves the page, which matters if either one encodes internal project, customer, or environment names you’d rather not send anywhere.