Starting from Junos OS 15.1, the J-Web package is included in junos-install and therefore, will not be available on the Juniper Networks Download Software site. This article details how to install the J-Web package optionally when required.  

Starting from Junos OS 15.1, the freebsd kernel 10.1 version is supported and these images are called  junos-install . 

For junos-install packages, the J-Web package is built-in and optional, which means that it can be enabled when required.

To enable the J-Web package optionally, execute the following command:

> request system software add optional://jweb

This change for MX is from release 15.1 onward.