Notepad++ can do search and replace in all open files with one command.
And it can open a lot of files at the same time if you select them in File Explorer, right click and select Edit in Notepad++
And it's free.
But, alas, it's interactive, not really batch. But if you skip that part of your requirements, it seems useful.
Dear Forum,
is it possible to batch-edit attributes for several HTML files, like Author, Title, Language, Description?
Sort of Mp3Tag, or epub Metadata Editor, I mean, but specific for HTML.
A little open-source utility, maybe?
Thank you!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic