How can I test my front end for accessibility to the blind?
I'd like my web front end to be accessible, including to people who use screen readers. I know the basics about labels and alt text for images, but there are some areas where I'm not sure what a screen reader will do and I'd like to find out and catch it if we're doing it badly. I don't want to actually buy my own screen reader, though, and also I'd like other people on my team to do this kind of testing on their parts before committing their changes too.
What tools are available to test for screen-reader accessibility? Is there a tool that can perform some sort of validation? A tool we could use locally would be better, but an online tool that checks a live web site would be ok (we can deploy a test server if we need to).