Keratin treatment/Japanese hair straightening/Similar places that don't use formaldehyde?

As the name - what are some salons that provide permanent hair straightening without using products with formaldehyde and/or have less toxic chemicals? I'm still on the fence, and part of it is because I'm reading about certain treatments being toxic (in which case I wouldn't want to do it) and would love to hear about the salons that offer this.