The problem CoinPay solves

To onboard the next billion people into crypto, many of the next users should not even have to know they're using crypto under the hood. CoinPay is a new P2P payment app that levarages the advantages of the blockchain without users even having to know. Benefit from transaction finality, no transaction limits, and no area restrictions. Onboard using your phone number and have a wallet auto generated for you, without you having to manage a seed phrase. Instantly be able to request or send US Dollars to anyone in the world instantly, no limits. All transactions are sent with comments memos and support emojis. Look up usernames, phone numbers, or emails, no copy/pasting wallet addresses.

Challenges I ran into

I was hoping to leverage the Coinbase Smart Wallet for this project however the sdk does not currently support React Native. I wanted to build this app to be very user accessible so mobile first was an important design decision. I pivotted to using Privy to allow for simply onboarding and account creation.

To be able send comments with send/request transactions, I was originally going to do a valueless transaction containing the comment in the data field but with no user op bundles, there was a serious performance and cost impact. I built around this by standing up complete CRUD services on aws offchain that match base transaction hashes to comments.

Given more time, I'd like to improve the user onboarding experience such as spinning up some ENS subdomain resolution to create onchain usernames for users upon login, or leverage coinbase's existing cb.id ENS subdomain.