Interchange
A study system I built for myself to learn payments properly: thirteen modules, from card rails at the wire level through licensing and regulation. Not a product — just the thing I used to get the knowledge in.
- Role
- Built for my own use
- Period
- 2026
- Type
- Study system
Why I built it
You can get a long way in payments on surface knowledge, which is the problem. Saying a platform supports ACH is easy. Knowing the return windows, when money actually settles, and how reconciliation behaves when it doesn’t is a different job, and the gap between the two tends to show up as money quietly going missing rather than as an error anyone can see.
I’d picked most of this up in fragments across different roles. This was me sitting down and doing it deliberately instead: 13 modules, 143 units, 337 review cards, ending in a capstone that forces the pieces to work together.
By the numbers
The domain, mapped
- Card rails — the four-party model down to ISO 8583 / EMV wire level
- Bank rails — ACH, wires, FedNow/RTP, SEPA, FPS, Pix, UPI
- Cross-border & FX
- Fraud & disputes
- Payments operations & ledger engineering
- Vendor vetting & implementation
- The partner capability stack — virtual banking accounts, wallets, ledgers, liquidity providers, payout networks
- Stablecoins, crypto wallet issuance, custody, ramps, on-chain reconciliation
- Licensing & regulation — MSB/MTL, EMI/PI, MiCA/VASP, AML, sanctions, Reg E, PCI
- Contracts, commercials & payments data — ending in a global-launch capstone
Honest state
This one is personal and runs locally. It isn’t a product, isn’t for sale, and there’s nothing to demo. It’s here because plenty of people claim payments depth and can’t show you anything behind it. This is what mine looks like.