First ensure that you check for concrete details such as the location where their offices are or the physical address. Then check on their website for any contact numbers and call to find out who answers. If the call is not answered, then that shows that it is an anonymous call centre. This should be a warning sign that there is a probability of the company been illegal. Check on the same website the physical address and clarify if that is where their offices are. If they are registered to that address, the better it is.
Check for online forums where the company is mentioned to find out their publicity. A customer complaining shows that they may be illegal or their services are below the customer expectations. Using a popular search engine like Google can help you find this information. It might not be always true what others write or talk about the company but you are new to the company and the information will guide on your decision.
Use the authorities’ online domains and libraries to check out for authenticity. The central banking system database has the authenticated companies licensed to conduct financial services. If they are not in that database, avoid them.