filterss 
filterss is a tool for filtering RSS or Atom feeds based on keywords.
Simply enter the URL of the feed you want to filter, your keyword(s), and we will provide a new URL for your filtered feed.
Free, no ads, no tracking. The code source of this tool is available as an example on github.
URL:
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This online tool is just a wrapper for my filterss project. It is free, open-source, and available on github, under the GPLv3 licence.
About
filterss is a project developped by Thomas Muguet.