Decimal
money, never floats, in every project
Jeffrey Jorgensen · backend engineer
Systems where the money has to add up.
Custodial wallets, multi-chain payouts and double-entry ledgers, taken from database schema to production. Every figure is dimensioned: it carries its source, its network and the instant it was taken. For payment companies, marketplaces and fintech teams whose numbers have to reconcile, and currently don't.
Reconciliation — the equation that must hold
Δ chain
on-chain holding
=
in
external in
−
out
external out
−
fees
fees paid
−
gas
gas moved
Internal transfers are excluded: they must sum to 0.00 across the system. Each term computed separately, so a discrepancy points at where to look rather than merely existing.
Production signals — from systems in real use, not a résumé
23,400
automated tests across every repository
313
API endpoints in the financial model
4
blockchain rails at the exchange
Isolated
the exchange's signing keys, never in the app
2
products on one core: exchange and payouts
1 yr
financial model in daily production, one engineer
MIT
open-source tool you can read
Sheet 01 — Parts list
Three kinds of problem, one requirement
All three share the same constraint: a number in the system has to be defensible, traceable to where it came from. That constraint is what I'm good at.
P-1
Payments
Rails & custodial wallets: receiving with source attribution across many addresses, batch payouts to hundreds of recipients, recurring debits, screening on the way in.Bitcoin · Ethereum · Tron · TON · signing keys isolated from the app
P-2
Ledgers
Double-entry accounting cores, the system of record under a wallet, exchange or marketplace balance: accounts, postings, holds, reconciliation, fees, audit trail.Decimal money, never floats · reconciliation against the chain · every balance traces to its postings
P-3
Documents
Financial data pipelines: bank statements, invoices, receipts and tax forms turned into decisions, not just extracted fields.PDF · OCR scans · spreadsheets · XML · output back into CRM, sheets or a filing package
Sheet 02 — Proof you can check
Don't take my word for it
Sheet 03 — Where to look next
Two ways to check my work
Two more: safeguards that reported success without working, and ten sentences about moving money that read like axioms and are false. All teardowns →
Sheet 04 — Ways in
Tell me what's breaking.
Thirty minutes, no preparation needed. You describe what happens today and what should happen instead; I tell you whether I'm the right person for it, including when the answer is no.
$1,800
Fixed-price audit · five working days · yours to keep, no obligation
from $14,000
One hard component: a ledger, a payout flow, a document pipeline
from $35,000
The whole system: schema, backend, interface, deploy, monitoring