Does the Amazon history price checker by URL actually work for tracking past prices? or How reliable

Yeah, some of these tools are trash.

But Keepa and CamelCamelCamel are legit. They even let you see price history for third-party sellers, which is handy.

Also, if you’re into browser extensions, The Camelizer (by CamelCamelCamel) is super convenient. Just click and see the price graph.

Just don’t fall for the ones that ask for payment. Most good tools are free.