Every cent accounted for.
I'm Serhii Horobets, a payments engineer with 20 years in banking and fintech. Serhard is my practice: I find the places where payment systems lose, duplicate or lose track of money, and help your team fix them.
| Payment | Your ledger | PSP settled |
|---|---|---|
| pay_8F21 | 1,250.00 | 1,250.00 |
| pay_8F22 | 89.90 | 89.90 |
| pay_8F23 | 420.00 | 420.00 |
| pay_8F24 | 15.00 | 15.00 |
| Unexplained difference | 0.00 | |
What I do
Three ways to work together, from a fixed-price review to hands-on help. Most clients start with the audit.
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Payment Integrity AuditFor fintechs, EMIs and PSPs moving real money
A two-week review of idempotency, retries, webhooks, ledger design and reconciliation, traced through your real code and data. Written findings ranked by money at risk, each with a fix.
From €3,500Fixed price, two weeksHow the audit works -
Load and resilience sprintBefore a launch, a promotion or a listing
A load model of your real traffic, a test suite your team keeps, and a report of what breaks first and how to fix it. Run against staging with JMeter or k6.
Fixed scopeUsually two weeks, quoted after a callAsk about a sprint -
Fixes and tech leadershipAfter an audit, or when you need a senior engineer
I implement the fixes alongside your team, or join a few hours a week as a fractional tech lead for architecture reviews, payment design and hiring.
Day rate or monthlyAgreed per engagementTalk about your project
Where the experience comes from
Twenty years of building and running systems where a wrong number is a real loss, not a bug report.
- Core and corporate banking
- Accounts, ledgers and payment orders inside core banking systems.
- Card and account-to-account payments
- PSP integrations, webhooks, refunds, chargebacks and settlement.
- KYC/AML and onboarding
- Verification flows, status machines and audit trails for regulated firms.
- Crypto and bank integrations
- Fiat on- and off-ramps between exchanges and banks.
- High-load platforms
- Performance engineering for iGaming and peak-traffic payment flows.
- Security and compliance
- PCI DSS scope, cryptography and bank-grade identity.
How I work
Small, clear engagements with a written result.
Fixed scope, fixed price
You know the cost before we start. No hourly meter running on audits.
Specific findings
Each issue comes with the scenario that triggers it and a fix an engineer can pick up.
Done by me
No hand-off to a junior team. You talk to the person reading your code.
Confidential by default
NDA as standard. Read-only access is enough for an audit.
Plain reports
Written so your CTO and your compliance team can both act on them.
EU-based
Wrocław, Poland. Central European time, invoiced in EUR.
Who you'll work with
I'm a fullstack engineer and tech lead. I've built and run core banking, corporate banking and payment platforms, KYC/AML flows and bank integrations for crypto exchanges, and led teams of senior engineers and QA through them.
Serhard joins my first name with -hard, the old ending for "strong". The ledger in the logo is the job: three entries, and the one that doesn't balance gets flagged.
- Experience20 years in IT
- DomainsBanking, payments, KYC/AML, PCI DSS
- Stack.NET, Node.js/NestJS, React, SQL Server, PostgreSQL, Oracle
- CloudAzure, AWS, GCP, Kubernetes, Terraform
- Based inWrocław, Poland
Check your own system first
The 30 payment failure modes I look for, as a checklist your team can run through in an afternoon. Free, no sign-up.
Talk to me
Tell me what you process (card, account-to-account, crypto), roughly how many transactions a month, and what's worrying you. I reply within one working day.