I use Picasa for photo editing among other apps, that has sepia option and it's pretty good filter. I would recommend Pixlr, which is also good to do edits and both are free. Pixlr has many sepia and monochrome filters.
However, I like these photos that you've uploaded as they are. They look better as they are 🙂
Thank you very much.
My pleasure, I hope you can find an app that works for you and participate in whatever challenge you like. I have a challenge called #monocolorsepia, in which you post all three versions: black and white, color and sepia. The main idea is to see which one looks better. Buildings for example usually look better in black and white, old things look better using a sepia filter, nature looks better as it is.
The beauty of editing is to find the best filter.
Anyway, sorry for the long reply, enjoy your editing process and have a nice weekend 😊