A few months ago, I started using vinegar instead of fabric softener.
I haven't really noticed a difference.
I wasn't sure how well it would work after it got nice enough to hang clothes outside, but I've hung them outside for the last few weeks, and it's not a problem. The clothes get stiff, but no worse than when I wash them with fabric softener.
(The exception was the summer that I lost the cap for the fabric softener - man, my clothes were soft that summer.)
A bottle of fabric softener lasts a long time, and I was afraid I'd go through vinegar a lot quicker, but I'm still on my first bottle. I haven't done the math to see which is cheaper, but I suspect it's vinegar. It's also a lot fewer weird chemicals, which is really my motivation.
I'm glad I tried it.
18 hours ago