Stablecoins × 3DS · Interactive
Parity
I spend my days on the layer of card rails that decides who’s real and who pays when they aren’t. This is that experience, pointed at stablecoins — one problem chosen, one fix proposed, six calculators to argue with.
The why, in one breath
A card payment quietly answers three questions — is the card real, is the person real, who pays when it goes wrong. A stablecoin payment answers almost none of them. Parity takes the biggest gap — refunds and disputes — designs three fixes, and prices everything with calculators you can play with.
What I do at Visa
3-D Secure platform: Visa Payment Passkey (FIDO/WebAuthn), network tokens, enriched authorization data, and the economics that make merchants say yes.
Why it transfers
Every rail must answer the same three questions — credential, person, loss. Card rails answer them so quietly merchants forget they’re questions.
The problem I chose
Chargebacks are the feature crypto forgot to copy. On an irreversible rail there is no dispute process — so I designed three, and priced them.
The thesis, drawn
The POC · featured problem
Chargebacks are the feature crypto forgot to copy.
On card rails, a cardholder who gets a brick instead of a laptop has a process — and if the transaction was 3DS-authenticated, the fraud loss has already shifted to the issuer by design. On a stablecoin rail, a refund is just a new payment the merchant may or may not send. So the POC proposes three dispute mechanisms and prices each one.
The pattern worth porting is liability shift as an incentive: whoever attests — to delivery, identity, or escrow release — carries the loss when the attestation is wrong. Loss allocation is the product; everything else is plumbing.
The rest of the balance sheet · five surfaces
$100 arrives as USDC. Walk the deck.
Pick a ticket, a volume, a policy — and compare the all-in cost of each path against card interchange. Illustrative rates.
A merchant holding $50,000 of a stablecoin is an unsecured creditor of its issuer. Fictional composite issuer, illustrative data.
- Instrument
- USD stablecoin · 1:1 redemption claim
- Attestation
- Monthly, point-in-time (demo)
- Redemption
- Business days; issuer may gate size
“Fully reserved” guarantees that at one instant, reserves ≥ tokens. It does not guarantee an audit, anything between attestation dates, or redemption at par, at speed, in stress. Holding the coin is credit exposure — card rails never ask a merchant to underwrite their acquirer.
“Convert to fiat” is one button and five parties. Illustrative timing.
- Merchant sends 50,000 USDC to the issuer’s redemption address
- Chain transfer finalises in seconds
- Issuer burns the tokens; supply drops, the claim is extinguished
- Issuer → bank instructs release of $50,000 from reserves
- Banking rail wire or ACH carries the fiat; this is where the clock lives
- Merchant bank funds land, same-day to T+1 (demo) — card speed, because the last leg is the same rail
Not a feature list — a decision. Pick one and read what you agreed to.
“Hold” is a position, not a default. Illustrative data.
North star: repeat acceptance. ★
Signup counts and gross volume inflate with incentives. A merchant who accepts a stablecoin twice, unprompted, has adopted a rail; one who accepts once has run an experiment.
activation ratestablecoin settlement shareall-in cost deltarefund resolution timedisputed volume %