Why this exists

Fintech engineering has no school

If you want to learn web development there are bootcamps, tutorials, free courses, books, YouTube channels, and a global community on Discord. If you want to learn fintech engineering specifically, the kind that touches real money, real customer wallets, real regulatory exposure, you mostly learn it by shipping it wrong in production and fixing it later.

That's how I learned. That's how almost everyone I know in this field learned. The first time you discover that wallet.balance is a lie, that webhooks fire twice, that "we'll add the idempotency keys later" leaves you with months of corrupted entries to reconcile, you remember it for the rest of your career. But the cost of that lesson was paid by customers and regulators and the companies that hired you. And the next engineer who joins your team has to learn it the same way unless someone wrote it down.

Nobody writes it down. Or rather, fragments of it are written down across hundreds of blog posts, post-mortems, RFCs, and Stripe docs, but nobody has put it all in one place where a junior engineer joining a fintech can spend a weekend reading and come out the other side with the mental model that took the rest of us five years to assemble.

So I'm writing it down

Fintech Lab is that resource. 85 lessons, each one walks through a real engineering pattern with a real journal entry against a real Postgres ledger you can post to in your browser. Six replayable incidents put you in the on-call seat of famous fintech moments and ask you what you'd do. Daily drills keep the patterns fresh. A growing library of bug-fix challenges, schema design exercises, and architectural decision questions force the patterns from "I read that once" into "I can do that in my sleep".

It's not a course you finish; it's a reference you grow with. New patterns get added when I encounter them in the wild. Existing lessons get sharpened when readers tell me what's unclear.

It's free and it stays free

No paywall, no upsell, no mailing list, no "premium tier", no certificate-as-a-service, no $497 founding-member offer. The curriculum, the sandbox, the drills, the incident replays, all of it is free. Sign up, work through it at your pace, delete your account in two clicks when you're done. That's the deal.

I'm not building this to monetize you. This exists because someone should have built it for me a decade ago, and since nobody did, I'm building it for the next person.

What I'd ask in return

Two things, neither obligatory.

First: if you find a lesson confusing, a pattern explained badly, or a bug, tell me. There's a feedback page that takes 30 seconds. I read every submission. The curriculum improves because readers tell me what doesn't land.

Second: if Fintech Lab helped you ship something real, or pass an interview, or finally understand why your previous employer's ledger was such a mess, share it with one engineer who'd benefit. That's how the audience grows. There's no ad budget. There's no growth team. There's just one person writing this and other engineers passing it along.