This is a free service with unlimited IMEI Checks, but the results are not very satisfying. You can find your iPhone model and some other basic stuff, but the SIM-Lock status, if it ever appears, it will be either unknown, or prompt you do buy it. Also, it looks like they promote Official iPhone unlocks, which is not always a good sign.
Tip for consumers: For general information (Not Network and SIM-Lock) it is a decent tool, but nothing more.
A free (for about 30 checks per day) IMEI Blacklist Check tool, which I believe it is mostly focusing on USA Mobile networks. It is not very accurate, but when it finds a blacklisted iPhone it will show you the reason of the blacklist status. Not the one that I would use for testing an iPhone that I am about to buy (except if it is a USA iPhone).
It may look like a simple iPhone IMEI Check service, but their staff is amazing. Not only did they guide me through the whole process and informed me which service I needed (based on what I told them), but they also provided me awesome support after my order. They even provided me feedback for the IMEI Unlock company I wanted to use. Their response time is about 3 minutes, and they provide you a full PDF report, so you can go back and check it anytime you want. Stayed 100% satisfied and they support Paypal too.
Tip for consumers: If you are not sure of the service you want to use, use their contact form. Based on your needs, they will inform you of which services you should order.