Our project is a catalog of B2B goods. There are 2 types of companies: free and paid. The problem is that 'free' companies cheat and create one more company with another name and contact data. They do that to fill completely category with their goods. Nevertheless 'paid' goods are listed above 'free' goods in catalog.

I thought about identification by:

  • cell phone with sms confirmation (cons: only small companies know what number they can fill in);
  • card number (cons: also is good only for small companies);
  • corporate e-mail (cons: even big companies in our database have no web site).

How would you do? Maybe I am wrong in my suggestions and it might be done in another way.


4 Answers 4


It is very difficult to prevent a motivated user from opening several accounts. Any way you choose will have drawbacks and work-arounds, or will be very tedious for your costumers.

It may be easier to try and catch the cheaters after they open additional accounts by looking for patterns with regards to IP, username, email, password,user-agent and such. You can also uses cookies or require a Credit Card on registration.

Here are some strategies you may try:

  • Set a tracking cookie and log its value on login, look for multiple logins from the same cookie value. There are cookies that work across browsers.
  • Logins from same IP address/user-agent combination
  • Look for accounts with email addresses from free webmail services
  • Look for accounts with same password
  • Check the contact info for patterns and overlap of the catelouges

Maybe you could implement some sort of verification from commercial registers (having them fill in their company-number and country). They could fill in another valid company-number but I think that would be against the law, so maybe this helps and works as deterrence.


I work at a company where we deal with that all the time. People want a catalog and what happens they just copy and go reselling on their own. What I did was before they access the the catalog, they have to fill out a form where they provide business name, address and tax ID or biz ID number, this way it weeds out all the scammers.


I'm not sure I'd bother trying to prevent the registration.

I'd look at the products themselves. Surely there must be some sort of identifier? Are the product pages directing back to a common URL? Common company name?

Basically group them together on a common element.

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