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Industry: Fintech & Finance

Software development for fintech

Engineering for payments, lending, neobanks, brokerage, and B2B fintech. We design PCI DSS scope down to almost nothing, build ledgers that reconcile to the penny, and wire KYC, AML, Open Banking, and fraud ML together without turning your product into a regulatory burden the team cannot ship against.

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Industry challenges we solve

Fintech is the rare category where a small engineering mistake becomes a regulatory letter rather than a Sentry alert. The work is to design systems where the boring path is also the compliant path.

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PCI DSS scope creep. A casual "let us log the request body for debugging" silently pulls your application servers into PCI scope and an SAQ D becomes inevitable. Annual audit costs double overnight.
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Reconciliation drifts at month end. The product shows one balance, the processor shows another, the bank statement disagrees with both. Finance closes the books late and confidence in the data quietly evaporates.
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KYC drop-off kills conversion. A clumsy onboarding flow loses 40% of applicants before they finish document upload. The marketing CAC ratio falls apart and growth stalls.
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Fraud detection bolted on as an afterthought. Rules engines accumulate without a holdout set, false positives explode, and the operations team spends more time on chargebacks than on the actual product.
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Legacy ledgers that nobody trusts. Spreadsheets reconciling MySQL totals against the payment processor, with a Python script run by one person who is about to leave. The audit trail is a ZIP file in Dropbox.
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Open Banking integrations that break weekly. Bank sandbox APIs diverge from production. Consent expires silently. Customers see a generic error and complain on Trustpilot.
Capabilities

Our fintech capabilities

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Payments orchestration

Stripe, Adyen, Checkout.com, Worldpay, Braintree, and Razorpay routed through a single orchestration layer with retry logic, 3DS handling, idempotency, automatic failover between providers, and per-currency cost optimisation.

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KYC, AML & identity

Onfido, Sumsub, Trulioo, Persona, Veriff, and ComplyAdvantage stitched into a provider agnostic journey. Sanctions, PEP, adverse media, ongoing monitoring, and a manual review console for the inevitable edge cases.

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Double-entry ledger engineering

Append only, immutable, idempotent ledgers on PostgreSQL or TigerBeetle. Strict double entry, deterministic replay, daily bank reconciliation, and a separation between the transactional core and reporting projections.

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Open Banking & PSD2

TrueLayer, Plaid, Yapily, Tink, and Salt Edge for aggregation, AIS, and PIS flows. SCA redirects, consent renewal, mandate management, and graceful fallback when a bank's API misbehaves.

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Fraud detection ML

Feature engineering pipelines on streaming data, gradient boosted models on Sift or in-house tooling, holdout sets to measure precision and recall honestly, and a decision engine that combines rules with model scores for explainability.

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Customer dashboards & reporting

Real time balances, statements, tax exports (1099, P60, P11D), Open Banking permission management, and CSV/PDF generation that holds up under HMRC, IRS, or DGT scrutiny.

Compliance & regulatory considerations

Fintech regulation is jurisdiction specific and changes faster than most software does. Below are the frameworks we design around on a routine engagement.

PCI DSS v4.0 SOC 2 Type 1 (in progress) FCA Handbook aware PSD2 / Open Banking GDPR & UK GDPR AML / KYC obligations CCPA UAE Data Protection Law

PCI DSS is solved by avoiding it. The cheapest compliant fintech is the one whose servers never see a card number. We push tokenisation into the processor's hosted fields, route raw PAN through Stripe Elements or Adyen Drop-in, and audit every log line that could accidentally capture sensitive authentication data. The result is SAQ A scope rather than SAQ D, which translates to a one day annual attestation instead of a four week audit programme.

FCA, SOC 2, and the rest are programmes we support, not certifications we sell. We are an engineering partner, not a regulatory consultancy. What we deliver is the evidence base: immutable audit logs, role based access with quarterly access reviews, customer money segregation, operational resilience playbooks aligned to PS21/3 impact tolerances, incident response runbooks tested with tabletop exercises, and the SOC 2 Type 1 control documentation if you choose to layer that on. SOC 2 Type 2 is your programme, run with your auditor. We pass the technical sections.

Sub-processor governance matters more than most teams realise. Every vendor that touches customer data ends up in a sub-processor register with its role, region, SOC 2 status, DPA, and renewal date. Where your contract requires advance approval before a sub-processor changes, we honour that with 30 days written notice and a written impact assessment.

Tech stack we use for fintech

Predictable, auditable infrastructure. Strong typing on the wire, deterministic replay in the ledger, and immutable logs by default.

Node.js 20 + TypeScript Go for ledger services React 18 + Next.js PostgreSQL 16 + TigerBeetle Redis + Kafka / SQS Temporal workflows Stripe, Adyen, Checkout.com Plaid, TrueLayer, Yapily Onfido, Sumsub, ComplyAdvantage AWS + IaC (Terraform) Auth0 / WorkOS + MFA Datadog + immutable audit logs
AI / ML Integration UK insurance broker · 12 weeks · adjacent fintech pattern

Document AI pipeline applicable to claims, KYC packs, and loan applications

The broker received three thousand monthly claims as a mix of PDFs, scans, and email attachments. We paired AWS Textract with GPT-4 structured outputs, validated each extracted field against the policy API, and added a rules plus ML triage lane. Eighty five percent of claims now clear in under four hours. The same pattern, document classification, structured extraction, validation against a system of record, confidence based routing, is exactly what fintech KYC packs, loan applications, and merchant onboarding need.

85%Auto triaged
4 hrsAvg processing (was 5 days)
96%Extraction accuracy
12 wksConcept to production

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FAQ

Common questions

Usually yes. The cleanest path is to never let card data touch your systems: Stripe Elements, Adyen Drop-in, or Checkout-hosted flows tokenise the PAN inside the processor's iframe. Your servers only ever see a token. That puts you in PCI DSS SAQ A territory rather than SAQ D, which removes about 90% of the audit burden. Where you genuinely need to hold pseudo-PAN data, we isolate the cardholder data environment with network segmentation, tokenisation vaults, and short-lived credentials.
We are not a regulatory consultancy and we will not pretend to be one. We are engineering aware of the FCA Handbook clauses that drive software design: SYSC operational resilience, SUP 15 incident reporting, CASS for client money handling, the FCA's Consumer Duty for retail products, and the operational resilience policy statement (PS21/3) on impact tolerances. We deliver the audit trails, immutable logs, segregation of client money, and incident playbooks your compliance team will be asked to produce, and we coordinate with your FCA legal counsel during build.
Onfido, Sumsub, Trulioo, Persona, Veriff, ComplyAdvantage, and SEON are the common ones. We build the orchestration layer that routes a customer through document verification, biometric checks, sanctions and PEP screening, address verification, and ongoing monitoring, with a manual review console for edge cases. The orchestration is provider agnostic so you can swap a vendor without rewriting the journey.
Yes, and we treat the ledger as the most important piece of code in the product. Strict double entry, append only, immutable, with idempotency keys on every write, deterministic replay, daily reconciliation against bank statements, and a separation between the transactional ledger and the reporting projections. We have built ledgers on PostgreSQL with strong consistency guarantees, and we are familiar with TigerBeetle when transaction throughput is the bottleneck.
Yes. TrueLayer, Plaid, Yapily, Tink, and Salt Edge for aggregation. We have built Account Information Service Provider and Payment Initiation Service Provider style flows for AIS/PIS use cases, including SCA redirects, consent renewals, and the messy edge cases when a bank's sandbox does not match production behaviour. For the US we use Plaid, Finicit, MX, and increasingly the new FedNow and RTP rails for instant payments.
Every third party service that processes customer data is documented in a sub-processor register with its role, region, SOC 2 status, DPA, and renewal date. We do not silently swap a vendor without telling you. Where your contract requires you to approve sub-processors in advance, we honour that and give you 30 days notice of any change.
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