Check the Samples
If a website offering list of US companies is completely legit, they won’t have any problems providing you with a sample list. Even if it’s only a couple hundred entries, it should be more than enough. To be sure, check a few companies at random. Open their website and see if the details match to those in the database.
If they have as many entries as they claim, such websites will have no problem to give you a sample with a few hundreds of them. If the opposite is the case, you better stay off from that website as the chances are high that they don’t have any contact details. Still, even if you get a free list from them, your work is not done. You need to make a couple more checks before paying for the list.
Pay Attention to Their Website