Platform core
Fintech infrastructure,
built to move real money.
We build the core that sits under your product. Ledger, accounts, rails, data and controls, owned by one EU team. It is designed for the day the volume arrives and the auditor asks how it works.
- EU-based engineers
- PSD2-aware design
- GDPR-compliant delivery
Scope
What sits inside the core
Six systems have to agree with each other, every second of the day. We build them as one product, on one plan, with one team accountable.
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01
Ledger core
A double-entry ledger is the single source of truth. Every balance can be rebuilt from its entries.
- Double-entry postings
- Idempotent writes
- Daily reconciliation
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02
Accounts & limits
Accounts, sub-accounts and holds in one model. Limits are rules, not code branches.
- Holds and releases
- Tiered limits
- Fee schedules
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03
Payment rails
SEPA, card and crypto rails behind one internal contract. Adding a rail stays a config job.
- SEPA and SEPA Instant
- Card acquiring links
- On-chain transfers
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04
Identity & risk
One onboarding flow feeds every product. Vendor swaps stay cheap because the flow is yours.
- KYC and KYB
- Sanctions screening
- Case review queue
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05
Data & reporting
An event log feeds the warehouse. Finance, risk and the regulator read the same numbers.
- Event sourcing
- Warehouse models
- Regulatory extracts
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06
Platform operations
You cannot run money you cannot see. Metrics, alerts and audit trails ship on day one.
- Service dashboards
- Immutable audit log
- 24/7 on-call runbooks
Architecture
Five layers, clean seams
Vendors change. Rules change. Your core should not. We keep the ledger free of vendor logic, so a new bank or chain is an adapter, not a rebuild.
Card and bank rails are covered on our payment gateway engineering page. Key handling sits with wallet and custody work.
- 01
Experience
Web and mobile clients, plus the back-office console your team works in.
- 02
Product services
Payments, wallets, cards and treasury logic. Each service owns its own data.
- 03
Platform core
Ledger, accounts, limits and the event log. This layer never depends on a vendor.
- 04
Rails & vendors
Banks, acquirers, custodians and chains sit behind adapters we own.
- 05
Controls & evidence
AML rules, retention, access control and audit trails cut across every layer.
Interfaces
How the core is reached
Each audience gets a named surface. Nobody queries the database directly.
| Surface | Shape | Guarantee |
|---|---|---|
| Public API | REST + webhooks | Versioned, signed, replay-safe |
| Streaming | WebSocket | Balances and payment status |
| Internal bus | Event log | Ordered, replayable, audited |
| Back office | Admin console | Roles, approvals, four-eyes |
| Finance | Batch extract | Daily ledger and fee files |
| Oversight | Report pack | Evidence for your auditor |
Delivery
From plan to production
Hardening is a phase, not a hope. We test failure before launch, not after it.
- 01
Discovery
2–4 weeks
Target architecture, rail list, control map and a costed delivery plan.
- 02
Core build
Iterative
Ledger, accounts and the event log built behind a hardened API.
- 03
Rail integration
In parallel
Banks, acquirers and chains wired in through adapters you own.
- 04
Hardening
Before launch
Load tests, failure drills, access review and an evidence pack.
- 05
Run
Ongoing
24/7 cover with named engineers. Roadmap work continues beside it.
Engagement
Four ways to buy the work
Scope shifts as you learn. The commercial model should shift with it.
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Fixed-scope build
A defined core, a fixed price, a dated plan. Best when the scope is settled.
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Dedicated team
A standing squad with a lead. Best for long roadmaps and steady releases.
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Staff augmentation
Senior engineers inside your team. Best when you own the plan already.
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CTO advisory
Architecture and hiring guidance. Best before you commit to a build.
Questions
Before you brief us
The four things buyers ask first. Bring the rest to the call.
Rule mapping is detailed on our compliance engineering page.
Do we have to replace our current core?
Rarely. We usually put a thin ledger and event log beside it. Traffic moves across in stages, not overnight.
Can you work inside our cloud account?
Yes. We deploy into your cloud, under your keys and your policies. You keep the accounts and the access.
How does compliance fit the build?
It runs beside the code, never after it. Our compliance engineering practice maps rules to controls as we go.
Who owns what we build?
You do. We build bespoke, client-owned systems. There is no white-label lock-in and no per-seat licence later.
Tell us what your core has to carry
Bring a rough scope and your rail list. We come back with an architecture view, a risk list and a costed plan. No demo theatre.