The EU Computer Programs Directive 2009 provides an exemption for reverse-engineering for the purposes of creating inter-operable systems. This directive has been harmonized into UK law (where Teller is domiciled and operates) and Teller satisfies the requirements to be protected by the exemption. We have also developed many novel techniques that do not meet the UK legal definition of reverse-engineering so we have that angle too. This issue has also been looked at by expensive lawyers.

In terms of stability. It actually takes 6-12 months for a bank to get something into production. We are not talking about fast moving organisations here. We have not had a breakage with a supported integration in two years of beta testing.

We take many steps to ensure our traffic does not stand out to banks eager to actively interfere with Teller. Our clients perfectly emulate (100% API compatibility with their own) and make the same API calls in the same order etc. We also only make API calls as a result of user action, i.e. Teller does not poll or cause atypical traffic patterns. Finally have 100s of IP addresses and assign an IP address to a user for a period of time. All of this compounds to make Teller traffic look indistinguishable from their own mobile app traffic. The objective is to make it more likely they will block their own app traffic than block Teller as a string incentive to not interfere their customers' choice to use Teller enabled services.