Design: UX/UI, branding, illustartions.
frontend: Angular JS, React JS, Vue JS, HTML5/CCS3
Backend: Node JS, Ruby, C#, C++, Java, PHP, CMS: WordPress, OpenCart
Mobile: Java Android, Objective C, Swift

Blockchain: Etherium core, Bitcoin core, Solidity, Hyperledger, Stellar, 0x protocol, Bitcoin, Dash, XMR