NEL header

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The HTTP NEL response header is used to configure network request logging.

Header type	Response header

Syntax

http

NEL: { "report_to": "name_of_reporting_group", "max_age": 12345, "include_subdomains": false, "success_fraction": 0.0, "failure_fraction": 1.0 }

Specification
Network Error Logging # nel-response-header

This page was last modified on ⁨Nov 21, 2025⁩ by MDN contributors.