The interactive lab for fintech engineers
The fintech engineering school nobody built.
Most engineers piece together how fintech systems actually work by breaking things in production. Fintech Lab is the alternative: a real ledger you can post to, sandboxes you keep, lessons that teach the patterns behind ledgers, payments, lending, risk, and scale, and replayable incidents from the moments those patterns got tested in public.
Lesson 1 · Your first journal entry
A user deposits ₦10,000 into your fintech. Money lands in the bank. The wallet owes the user that amount. Post the journal entry.
85 lessons. 18 sections. One real ledger.
From your first journal entry to multi-region sharding, FX revaluation, and SAR workflow ledger ties. Pick a section, or follow a curated track.
Foundations
Debits, credits, the two-sided story.
State and lifecycle
Refunds, holds, segregation, reconciliation.
Accrual and engineering patterns
Recognition over time, releases, dedup keys.
Risk and operations
Where money goes wrong and how to record it.
Advanced and capstones
Multi-currency, audit, statements, reconciliation.
Issuing, lending, treasury
Issuing cards, lending money, and the sponsor-bank patterns underneath everything.
Risk and limits
KYC tiers, velocity gates, and AML holds, risk controls implemented at the ledger.
Distributed transactions
Outbox, sagas, maker-checker, patterns that keep money movement honest across systems.
Scale and concurrency
Projections, locks, rebuild paths, partitioning. How the ledger stays fast at billions of rows.
Operations and structure
Proration, reserves, multi-entity consolidation, FX revaluation. The reporting-side mechanics every CFO needs.
Payments rails
Push vs pull, instant systems, correspondent banking, the Wise model, 3DS step-up. The engineering inside the rails every fintech rides on.
Lending depth
DPD buckets, BNPL, revolving credit, restructuring, IFRS 9 ECL. The accounting that makes a loan book honest.
Card economics
Issuer vs acquirer, interchange / MDR breakdown, loyalty, network tokens, chargeback disputes. Where the basis points actually go.
Treasury
Liquidity laddering, float optimisation, FX hedging, capital adequacy, settlement netting. The CFO's quiet engine room.
Compliance flows
SAR workflow, sanctions / PEP screening, beneficial ownership, Travel Rule, AML monitoring. The regulator-facing ledger.
Crypto-fiat boundary
On-chain reconciliation, stablecoin reserves, hot / cold wallets, tax lots, failed-tx handling. Where chain truth meets ledger truth.
Reporting and close
Income statement, balance sheet, cash flow, footnotes, materiality. The financials your CFO actually publishes.
Engineering deeper
Event sourcing + CQRS, multi-region replication, sharding, WORM, column encryption. The architecture for ledgers at billions of rows.
You're on call. The peg just broke.
Walk famous fintech incidents from the engineer's seat at hour zero. Each replay pairs a multiple-choice decision with the journal entry that makes it real. The wrong calls are right there to click; the consequences land in the ledger.
Real ledger, not a toy
Every entry you post lands in a Postgres-backed double-entry ledger built the way production fintechs build them. You'll see why the wallet table is a lie.
Your own sandbox
Each lesson gets an isolated sandbox. Break it, reset it, export it as JSON. Come back tomorrow. Your state is yours.
From ledger to lending to scale
Card flows, P2P, settlements, chargebacks, idempotency, sagas, outbox, sharding, FX revaluation, multi-entity consolidation. The patterns that confuse engineers in their first year.
Code, not vibes
Every lesson ships SQL, TypeScript, Python, and Go snippets next to the journal entries. The bridge from accounting concept to the schema you'd actually deploy.
no upsell. no mailing list. no certification scam.
Free, and built for engineers who'd rather read code than slides.
You sign up, your sandbox is yours, your progress is yours, and you can delete it all in two clicks any time. That's the deal.