Do I need permission from a franchisor before I talk to its franchisees about the business?

No you don’t, and you are quite at liberty to write, email, telephone, or walk into a franchised outlet and ask the franchisee what they think about the business - and the franchisor - whenever you feel like it.  However, you are much more likely to get a polite response if your enquiry is expected and comes about following an introduction from the franchisor. Or you have at least made an appointment, explaining what you want to know and why.  Think about it from the franchisee’s point of view. Who is this person contacting them out of the blue, and why should they spend valuable selling time talking to someone who may not even be a serious potential franchisee? Until you are part-way through the franchisor’s recruitment process, there is no way of knowing whether you are likely to be acceptable to them, or vice-versa, so it is not reasonable to take up an operating franchisee’s time unnecessarily.  Ideally, at the right time, the franchisor will arrange for you to visit one, or some, of its franchisees who will be expecting you, and who will have a planned way of dealing with such visits, possibly even allowing you to work in the business for a day.