This repository implements a collector for the Reporting and Network Error Logging (NEL) specifications. These specs allow site owners to instruct browsers and other user agents to collect and report on reliability information about the site. This gives you the same information as you'd get from your server logs, but collected from your clients. This client-side data set will include information about failed requests that never made it to your serving infrastructure.

This repository provides a full working implementation of the collector side of the specs. If you run this collector behind a publicly available URL, you can use that URL in NEL configuration headers for your web site or service. NEL-compliant user agents will send reports about requests to your domain to this collector. You can then route them to a metrics or logs collection service for further analysis.