Runs locally
Duplicate bookmark finder and remover
Same link saved six times, plus a tracking-parameter twin. This finder groups them and lets you download a deduplicated Netscape file.
Then save the useful bits
These tools do not create a Markwise account. When you want the file in a library you can ask, start free and save a link. The file you just inspected is still on your machine.
Questions
Can I paste a list instead of a file?+
Yes. One URL per line works. Titles will be the URL unless you upload a bookmarks.html file that already has titles.
Will it delete bookmarks in Chrome?+
No. It only reads a file or pasted text and offers a download. Chrome is unchanged until you import a file yourself.