Fintech products need custom software. Compliance requirements make off-the-shelf impossible.
We build custom software for fintech startups — transaction engines, compliance workflows, KYC/AML integration, and the financial data infrastructure that processes money safely and accurately. Fixed scope, fixed price.
Plaid handles bank account connection. Stripe handles card processing. Neither of them handles your specific ledger logic, your transaction categorisation rules, or the compliance documentation your regulator or banking partner requires. That custom layer is what we build.
Fintech software has two problems that distinguish it from every other category of software. The first is correctness: money is not eventually consistent. Every transaction needs to debit and credit the right accounts simultaneously, idempotently, and completely. A payment that's charged but not credited is a real loss. A refund processed twice is a real cost. A ledger that doesn't balance to the penny is a compliance failure. Software that handles money needs to be built with the concurrency controls, idempotency keys, and double-entry accounting primitives that financial software requires.
The second problem is compliance. Most fintech products operate under a regulatory framework — state money transmitter licenses, bank partner compliance requirements, SEC registration, FinCEN BSA/AML program requirements — that mandates specific technical controls: customer identification, transaction monitoring, suspicious activity flagging, and audit trail completeness. These controls aren't optional features to add after launch; they're requirements that determine whether your bank partner will process transactions for you and whether your regulator will let you operate.
Off-the-shelf tools handle the payment rails (Stripe, Plaid, Synapse, Modern Treasury). They don't handle the custom ledger logic, the compliance workflow, or the transaction data model that your product requires. That's the custom layer.
Custom fintech software with a reliable transaction engine, KYC/AML compliance integration, audit-ready event logging, and the financial data model that supports your product's core logic — built with the correctness that financial software demands.
Double-entry ledger engine
Generalised ledger with account structure mapped to your product (user accounts, float account, fee account, reserve account). Every transaction creates balanced ledger entries atomically. Ledger is the authoritative financial record — reconciles to external payment rail statements daily.
KYC/AML integration and workflow
Identity verification via Persona or Alloy (SSN verification, document verification, watchlist screening). KYC tier configuration for your risk model. SAR/CTR workflow for reportable transactions. Ongoing monitoring triggers for behavioural anomalies.
Transaction processing with idempotency
Transaction submission to your payment rail (Stripe, Modern Treasury, Synapse, Dwolla) with idempotency key management and retry logic. Status polling and webhook processing for async settlement. Transaction state machine with all valid transitions and associated ledger entries.
Compliance event log
Immutable event log of every user action, transaction, and system event relevant to compliance — formatted for export to your compliance management system or directly to regulators.
Reporting and reconciliation
Daily settlement reconciliation between the ledger and payment rail statements. Exception workflow for unmatched items. Management reporting: float position, revenue by transaction type, and fee income. Built on Next.js, Postgres with row-level locking for transaction atomicity, Persona/Alloy for KYC, and integration with your specific payment rail.
One honest number to start.
Fixed-scope, fixed-price. The number below is the starting point — final scope is built from your brief.
Custom fintech software with a reliable transaction engine, KYC/AML compliance integration, audit-ready event logging, and the financial data model that supports your product's core logic — built with the correctness that financial software demands.
Three steps, every time.
The same repeatable engagement on every project. No surprises, no mystery, no billable ambiguity.
Brief & discovery.
We send you questions, then get on a call. Output: a written scope with every step, feature, and integration listed.
Build & ship.
Fixed schedule, weekly reviews. No scope creep unless you change the scope — and if you do, we reprice it transparently.
Warranty & retainer.
30-day warranty on every launch. Most clients stay on a monthly retainer for ongoing features and maintenance.
Why Fixed-Price Matters Here
Fintech founders are often in negotiation with bank partners or investors, and the technology scope is a line item in those conversations. A defined cost for the custom infrastructure layer — not an open-ended hourly engagement — is what those conversations need. Fixed scope, fixed price.
Related engagements.
Questions, answered.
We provide technical due diligence on payment rail options based on your product's transaction types, target geographies, and volume. Bank partner and BaaS provider selection is your decision with your legal and compliance advisors. We integrate with the rail you select.
Multi-currency requires an additional FX layer — spot rate capture at transaction time, FX gain/loss accounting, and reporting in functional currency. This is in scope for products that need it; it's a defined addition to the core ledger.
Yes — the event log exports in standard formats (JSON, CSV) and we integrate with compliance platforms (Hummingbird, Comply Advantage, Unit21) via API for automated case management.
Ledger engine, KYC/AML integration, transaction processing, and compliance logging typically runs $50k–$120k depending on payment rail complexity and compliance requirements. Fixed-price.
14 to 20 weeks for a production-ready fintech infrastructure layer. Compliance review milestones are built into the timeline.
Tell Ryel about your project.
Describe what you’re building and what outcome you need. You’ll have a written, fixed-price scope within the week.