I know you have a swatter, but hear me out: electrical swatter. So much less effort. Great for mosquitoes outside too. https://www.amazon.com/gp/product/B076CL94FF/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Get a cat. My cat has assassinated flies within <5 seconds of spotting one.

If you mean gnats, sticky traps.

We live in an area with lots of flies (rural horse country -- we don't have horses but neighbors do) and the only thing we've found that works is to use an electric fly swatter from Amazon. This thing is a true miracle product. I know you're saying you want something with minimal effort -- this does require some effort and has a bit of a learning curve, but once you get used to it, it's *way* less work and dramatically more effective than a regular non-electric swatter.

https://www.amazon.com/FOBELISK-Bug-Zapper-Electric-Batteries/dp/B07RQP31ZQ/ref=asc_df_B07RQP31ZQ/?tag=hyprod-20&linkCode=df0&hvadid=366327447072&hvpos=&hvnetw=g&hvrand=13279936417720673266&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9007567&hvtargid=pla-813612366450&psc=1&tag=&ref=&adgrpid=75870826946&hvpone=&hvptwo=&hvadid=366327447072&hvpos=&hvnetw=g&hvrand=13279936417720673266&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9007567&hvtargid=pla-813612366450

Save a powerful spray bottle and fill it with water. Then you can just spray the fly until it falls down. It works if they’re landed or flying.

Thanks! To be clear, I already have a swatter and I can catch them that way. I was looking for a solution that requires minimal effort in my part (including the effort of having to clean a jar of dead flies.)

I bought this from Amazon out of frustration. To my surprise, it worked very well. I caught at least 14 flies with this. Other methods didn't work.

RESTCLOUD Insect and Butterfly Net with 12" Ring, 24" Net Depth

Same thing you hang in a barn. Sticky fly strips hung out of the way.

Shpritz them with Fantastic or Windex when they land. That's the only thing you can do.

In Bethesda, every time we open a door or window (even with screens) flies come in. Not a ton, but 2-3, enough to drive me crazy. I chase them with a swatter but there must be a better way. Are the vinegar jars effective? Is it gross to empty them out? Any store-bought traps that work?