What type of VPC endpoint incurs no additional charge?

Gateway endpoints incur no additional charge because they are designed to provide a direct route to specific AWS services, such as Amazon S3 and DynamoDB, without the need for an NAT gateway or public IP addresses. This setup allows traffic to flow directly within the Amazon network, optimizing performance and security while avoiding extra costs associated with data transfer over the public internet.

In contrast, interface endpoints and other types of data transfer endpoints typically involve charges related to data processing and transfer. Peering connections, while facilitating network traffic between different VPCs, can also incur costs depending on the data usage and the specifics of the connection. Therefore, gateway endpoints stand out as an economical choice for routing traffic to certain AWS services without incurring extra fees.