Ask the provider to describe the input, the output, and a case the tool cannot resolve.
Guide / Comparing alternatives
A Veriftools alternative should solve your actual problem.
Start by naming the check you need. A fast answer is no help if it answers a different question.
Before searching for a Veriftools alternative, write down the decision you are trying to make. Do you need to read a damaged scan, check where an image came from, or review conflicting records about a person? Those jobs require different evidence. A product that handles one may not handle the others.
OnlyFake.me has not run a comparative test of providers, so this page does not score them. It gives you a way to read their claims and find out where their limits begin. You can also read the questions to ask about Veriftools.
Three checks
Compare what you can verify.
Find out how submitted files are handled and who can see them.
If a result affects a person, look for a way to correct the record.