X-Seen-By
The HTTP X-Seen-By unofficial response header is sent by Wix infrastructure to expose which internal nodes handled a request.
Note
The "X-" naming convention for HTTP headers, "X" referring to "experimental", has been deprecated and needs to be transitioned to the formal naming convention for HTTP headers.
Usage
Wix runs its hosting platform on layered infrastructure: load balancers, application servers, and Caching systems. The X-Seen-By header records which nodes processed a given request as the request traveled through those layers.
Each node appends its identifier to the header before passing the request or response along. The result is a comma-separated list of Base64-encoded hashes, one per node. The hashes are opaque: internal identifiers meaningful only to Wix engineers diagnosing infrastructure issues.
The header appears on responses from Wix-hosted sites, typically
together with Wix's Server: Pepyaka signature. The header often
appears alongside GLB-X-Seen-By, which records
the same information from the global load balancer layer.
Values
Node identifier list
The header value is a comma-separated list of Base64-encoded strings. Each string identifies one infrastructure node in the request path. The order reflects the sequence in which the nodes handled the request.
Example
A simple response routed through two internal nodes shows two comma-separated Base64 hashes. The values have no meaning to external clients and are used for internal log correlation.
X-Seen-By: yvSunuo/8ld62ehjr5B7kA==,T7xPrjRFKDMHVv938PYVfx9slopJdhD+WySraMrpIY8=
Requests with more complex routing paths include additional entries. Each added hash corresponds to another layer in the Wix infrastructure stack.
X-Seen-By: yvSunuo/8ld62ehjr5B7kA==,T7xPrjRFKDMHVv938PYVfx9slopJdhD+WySraMrpIY8=,4kqI2T4hfJQ2y3Ke0kY7Vw==
The header typically appears alongside X-Request-Id for end-to-end request tracing across Wix's systems.