GLB-X-Seen-By
The HTTP GLB-X-Seen-By response header is an unofficial header sent by Wix, recording which global load balancer node handled the request at the outermost layer of the Wix hosting infrastructure.
Usage
Wix operates a global load balancer (GLB) tier in front of its application infrastructure. When a request arrives at a Wix-hosted site, the GLB layer processes the request first before routing to regional application servers and caches.
The GLB-X-Seen-By header is set by the GLB layer and contains a single Base64-encoded hash identifying the specific global load balancer node receiving the request. The "GLB" prefix distinguishes this header from X-Seen-By, which records nodes deeper in the infrastructure stack.
Both headers serve the same diagnostic purpose: giving Wix
engineers a trace of where in the infrastructure a request traveled.
The values are opaque identifiers with no meaning to external
clients. The two headers commonly appear together on responses from
Wix-hosted sites, alongside the Server: Pepyaka signature of the
Wix edge, providing a layered view from the global entry point
through to the internal application nodes.
Values
Global load balancer node hash
The header value is a single Base64-encoded hash identifying the GLB node. Unlike X-Seen-By, which accumulates multiple node identifiers, GLB-X-Seen-By reflects only the single entry point at the global load balancing layer.
Example
The value is a Base64-encoded string mapping to a specific node in the Wix global load balancer fleet. The value is opaque and stable for a given node, but meaningless outside the Wix internal systems.
GLB-X-Seen-By: bS8wRlGzu0Hc+WrYuHB8QIg44yfcdCMJRkBoQ1h6Vjc=
The header typically appears alongside X-Seen-By on the same response. Together they provide a trace from the global entry point through the internal application infrastructure.
GLB-X-Seen-By: bS8wRlGzu0Hc+WrYuHB8QIg44yfcdCMJRkBoQ1h6Vjc=
X-Seen-By: yvSunuo/8ld62ehjr5B7kA==,T7xPrjRFKDMHVv938PYVfx9slopJdhD+WySraMrpIY8=
Observed in the wild
In crawl data, every host observed sending
GLB-X-Seen-By sits on Wix infrastructure,
mostly Wix-hosted custom domains with a handful of
wixsite.com subdomains, and every one also sends
X-Seen-By. The two
headers describe the same Wix request path at
different depths, with the GLB prefix marking the
global load balancer at the outermost layer.
Values are base64 strings identifying the balancer node rather than carrying meaning a visitor decodes. One value dominates the observations, appearing on most responses across many sites, which is consistent with a small pool of global balancer nodes fronting the whole platform.
The practical reading mirrors the rest of the
X-Seen-By family: a debugging trail through Wix
infrastructure, useful when correlating a slow or
failed response with the node handling the request,
and noise for everyone else.