# Optional HTTP headers

EventStoreDB supports custom HTTP headers for requests. The headers were previously in the form X-ES-ExpectedVersion but were changed to ES-ExpectedVersion in compliance with RFC-6648 (opens new window).

The headers supported are:

Header Description
ES-ExpectedVersion The expected version of the stream (allows optimistic concurrency)
ES-ResolveLinkTo Whether to resolve linkTos in stream
ES-RequiresMaster Whether this operation needs to run on the master node
ES-TrustedAuth Allows a trusted intermediary to handle authentication
ES-LongPoll Instructs the server to do a long poll operation on a stream read
ES-HardDelete Instructs the server to hard delete the stream when deleting as opposed to the default soft delete
ES-EventType Instructs the server the event type associated to a posted body
ES-EventId Instructs the server the event id associated to a posted body