Feral Cat Coalition (FCCO) offers a few different spay/neuter services for feral, stray and pet cats. Please see their webpage for more information regarding the services they offer. They are doing amazing work for cats, and we know from our own experience, they truly care about all cats. FCCO is solely funded by donation
Alley Cat Allies: This organization is one of the largest groups advocating for feral and stray cats. "We are a resource for tens of thousands of dedicated cat caregivers, advocates, nonprofit groups, and volunteers driving change and accelerating protection for millions of cats worldwide." (Alley Cat Allies). Their website is a great resource for information on TNR, community cat care, and related topics.