If you are building a decentralized wxchange then why is there need of KYC?
It is rare that DEX were asking for KYC,since it is mostly created for the purpose of trading anonymously.
This is a common question I'm seeing, and I've responded to it previously, but I will will respond to it again to add more details. The situation of KYC requirement is still evolving legally. The legal obligations of DEX is not clear, and DEX's like EtherDelta has been sued personally. Furthermore, even big DEX's like IDEX has moved toward requiring KYC.
As the legal landscape continues to evolve, I think it is important to acknowledge that the status of KYC requirement is not settled, and to be transparent about it. There is no point in ignoring the legal pressure that governments can apply. For us, we're following the Airswap model where KYC is optional and I think it is a balanced compromise, but if the situation change we will inform our community.