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Tag: fintech

4 articles tagged “fintech” on Oak Oliver Engineering, newest first. The latest is “I Built Two Stripe Integrations in the Same Codebase. They Share Almost Zero Billing Code.”.

Architecture

I Built Two Stripe Integrations in the Same Codebase. They Share Almost Zero Billing Code.

Why per-session payments and prepaid credit systems demand completely different architectures — even when they use the same Stripe account, the same API keys, and the same developer.

February 9, 2026 9 min read
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Architecture

Stop Deducting Credits Immediately — Your Billing System Is a Ticking Time Bomb

Why naive credit deduction causes race conditions, phantom charges, and support nightmares — and how the hold-confirm-release pattern with automatic TTL expiration eliminates an entire category of billing bugs.

February 6, 2026 10 min read
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Architecture

Your SaaS Handles Money With a Balance Column. That's Why Your Numbers Don't Add Up at 2 AM.

How I built NostroLedger — a double-entry accounting system inside PostgreSQL that tracks every cent flowing through a real-time mentoring platform, and why 700-year-old bookkeeping principles will save your startup.

January 24, 2026 9 min read
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Architecture

Every User Gets Their Own Database. The Billing Architecture That Shouldn't Work — But Outperforms Everything.

How Vibe gives every user their own bank.sqlite for credits, holds, and transactions — the hold/confirm/release pattern, 5-minute TTL self-healing, and why database-per-user scales better than you think.

January 22, 2026 11 min read
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