The site's functionality was restored as I figured out a way to bring it back and keep it running at a low cost. It will not receive any further updates or bug fixes.
My browser extension has the same functionality and much more, like: In-browser inspect, trade locks, doppler phases, bookmarking, floats, trade site bumping and much more.
It's called CSGO Trader - Steam Trading Enhancer, you can find out more about it here:

What's trade locked?

Find out which items have trade restrictions and when they are tradable. Enter someone’s steam profile or trade link to load their inventory.

Steam profile or trade link:

Steam profile example:

Trade link example:

Or check an inventory directly by link.

What is a trade lock? At the end of March of 2018 Valve implemented a new update to CS:GO trading. They restrict the trading of newly received items by locking them to the account for 7 days. Once an inventory is loaded there is a countdown displayed for every item that marks the end of this seven-day trade cooldown.

This is what an inventory looks like when loaded and filtered to m4s, aks and m9s: