I'm actually working on Common Crawl datasets and I want to know the cost of transferring data from the original S3 bucket to my EC2 cluster ? Is there any charge or it's totally free ?
There is no charge for transferring data from S3 to EC2 within the same AWS region. The bucket owner pays transport charges and the EC2 owner will pay a negligible cross-region data charge for the upstream traffic (essentially just the initial request, and the TCP ACKs) for downloads from S3 to EC2 in a different region.
The aws-publicdatasets bucket is in the us-east-1 region.
Note that you can also monitor your estimated charges with billing alerts and avoid surprises.