Hello @criki,  No, PutS3Object itself does not perform MD5 integrity check.  This can be confirmed on the processor source code where we do not have any checksum method:  https://github.com/apache/nifi/blob/main/nifi-extension-bundles/nifi-aws-bundle/nifi-aws-processors/src/main/java/org/apache/nifi/processors/aws/s3/PutS3Object.java  On this link you can see how the SDK can configure the MD5 checksum, which is not part of the processor code:  https://docs.aws.amazon.com/AmazonS3/latest/userguide/checking-object-integrity-upload.html  What you can do is, in your Flow, add a hash and then review it.  First with CryptographicHashContent create the hash, then do the PutS3Object.  After that, you can confirm it is fine do FetchS3Object then CryptographicHashContent and compare the hash with RouteOnAttribute.  ... View more