No, success fees are generally seen as unethical. Depending on the grant, they may even be illegal. The experts in our marketplace set rates on hourly and/or project bases. You should be wary of grant writers who offer work on a success fee.
Note: OpenGrants does not offer grant writing services itself. OpenGrants is the marketplace that helps you connect with experienced grant writers and other experts, so you can hire the right person for your specific needs.