Can DynamoDB store blobs?

Yes, within limits. DynamoDB stores binary large objects (BLOBs) in Binary (B) attributes, base64-encoded on the wire, as long as the entire item stays under 400 KB. For anything larger — video, audio, high-resolution images — AWS recommends storing the blob in Amazon S3 and keeping only a reference and metadata in DynamoDB.

Storing a blob directly

Put the bytes in a Binary attribute. Applications base64-encode binary values before sending them; DynamoDB counts the raw byte length toward the 400 KB item size. Small blobs (signatures, compact payloads) fit comfortably.

The large-object pattern

When a blob exceeds 400 KB:

• Store the object in Amazon S3.
• Keep the S3 key plus metadata (name, size, owner, timestamps) in DynamoDB.

This pairs DynamoDB's fast indexed lookups with S3's cheap, unbounded object storage.

A caveat

There are no cross-service transactions between DynamoDB and S3, so your application must handle partial failures and orphaned objects itself.

Go deeper

Check sizes with the item size calculator and read the item size limit guide. Download DynoTable to view binary data.