Is there any free (as in free beer, i.e., no publication fees or other fees whatsoever), open-access (free and open access to everyone) and peer-reviewed mathematics journal?

I am interested in a list of journals. I am particularly interested in my field which is low dimensional topology and geometry and geometric group theory.

The observation how well a site like MathOverflow or Math Stack Exchange works makes me wonder if a similar system does exist for the peer-reviewing and publication process itself.

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