Building Stablecoin Payments at Scale | Justin Gainsley (Coinbase) at ETHConf

Sun, Aug 2, 2026, 12:00 AM

In this talk, Justin Gainsley, who leads stablecoin payment acceptance at Coinbase, shares what four years of building stablecoin payments at scale has taught him about selling to enterprises and payment service providers, and what still needs to be accomplished. He opens with a 2012 Hacker News post from Coinbase founder Brian Armstrong, written before he even applied to Y Combinator, expressing the idea of using crypto to remove the 2 to 3% interchange tax Visa and Mastercard charge on every payment, showing crypto as a payment method has been ingrained in Coinbase from the start. Taking over Coinbase Commerce with the same mandate, Justin's team tried nearly everything (Bitcoin payments, every token on every chain, memecoins, cashback, point of sale, invoicing, online checkout) but nothing moved the needle, and for a while they worried crypto might not be right for payments. The signal emerged from talking to hundreds of buyers and merchants: a real cohort wanted crypto as their cash, something stable to earn into and spend without gas or volatility. So Coinbase made the non-consensus bet of stripping out Bitcoin, Ethereum, and all volatile assets to go all in on stablecoins, which drew internal backlash but sent conversion, volume, and merchant satisfaction all up. Strikingly, 64% of wallets paying on the stablecoin only product held no other assets, a fundamentally new cohort of savers rather than traders. Justin recounts bringing what they thought was the industry's best stablecoin checkout to Shopify, only to be asked about auth and capture, a term he had never heard, kicking off a year of learning what a real payment system requires: authorization holds, automated voids, configurable expiries, refunds, settlement schemes, reconciliation, and disputes. He details the resulting open source Commerce Payments Protocol, an escrow smart contract on Base powering Shopify's USDC checkout across hundreds of thousands of sites, with a permissionless operator role, six operations (authorize, capture, charge, void, refund, reclaim), and a blockchain native reclaim function letting buyers pull funds back after expiry. He covers the boring but required enterprise needs (predictable flat gas fees, custom settlement files, daily fiat delivery, compliance), argues the blockchain itself is fine for payments since Base settles in 200 milliseconds for under a penny, and identifies wallets, on-ramps, and signing UX as the real problems. He closes noting stablecoin payments have gone from curiosity to production in two years. 00:00 Introduction 00:41 Brian Armstrong's 2012 Post on Removing Interchange 01:09 Why Crypto Payments Are in Coinbase's DNA 01:35 Trying Everything to Make Crypto Payments Work 02:00 Worrying Crypto Might Not Fit Payments 02:23 Listening Closely to Buyers and Merchants 02:41 The Camp That Wanted Crypto as Cash 03:06 The Non-Consensus Bet on Stablecoins 03:35 The Internal Backlash 03:58 Why All the Metrics Went Up 04:28 64% of Wallets Held No Other Assets 04:54 The New Cohort of Savers 05:14 Bringing the Best Checkout to Shopify 05:32 The Auth and Capture Question 06:08 A Year Learning What Payments Require 06:32 Why Not to Underestimate Traditional Payments 07:15 Plugging Into Where Enterprises Already Are 07:37 The Commerce Payments Protocol on Base 08:01 How the Escrow Smart Contract Works 08:28 The Operator Role Explained 08:46 Why Operators Cannot Modify or Lock Funds 09:28 The Six Core Operations 09:48 Reclaim as a Blockchain Native Feature 10:12 The Boring but Required Enterprise Needs 10:33 Predictable Flat Gas Fees 10:44 Custom Settlement Files per PSP 11:01 Daily Fiat Delivery and Compliance 11:26 Just Another Alternative Payment Method 11:54 What the Industry Still Needs 12:19 Why the Blockchain Is Fine for Payments 12:42 Where Wallet UX Kills Conversion 13:03 Why On-Ramps Still Need to Be Better 13:27 Signing UX and Smart Wallet Adoption 13:59 From Curiosity to Production in Two Years 14:41 Closing _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ *ETHConf 2026* ETHConf is a 3 day event for founders, industry leaders, and builders who are excited about the possibilities of building on top of Ethereum. Connect with 2,000+ top innovators in crypto, finance, technology, and policy at our inaugural three-day event packed with showcases, demos, partnerships, and conversations shaping the future of the global economy. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ✅ *Follow ETHConf* X: https://x.com/ethconf Website: https://ethconf.com _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 🎟️ Get your early bird tickets for ETHConf 2027: https://ethconf.com/2027#tickets 🎤 View the full ETHConf 2026 Speaker Schedule: https://ethconf.com/schedule _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _