Fintech, payments & banking

AI & Software Development for UK Fintech & Banking

We build customer apps, onboarding and KYC journeys, payment and Open Banking integrations, and the back-office tools behind them — for firms regulated by the FCA and the companies that supply them. Audit trails, approvals and customer outcomes are part of the design, not an afterthought.

  • Banking, wallet and money-transfer apps delivered
  • Card data kept off your servers by design
  • Audit trails and four-eyes approvals built in

Industry challenges

Why fintech builds take longer than planned.

The screens are rarely the hard part. The time goes on onboarding rules, payment edge cases, reconciliation and showing compliance that the product treats customers fairly.

Where better software pays off

  • Onboarding that clears straightforward applicants and routes the rest to an analyst
  • Automated reconciliation against provider and bank records
  • Complaints and outcomes data ready for Consumer Duty reporting
  • Pay-by-bank and account data inside your own app

Onboarding that loses good applicants

Identity, address and screening checks stitched together without a plan leave genuine customers stuck in manual review, and drop-off climbs with every extra step.

Money that does not reconcile

Your ledger, payment provider settlements and bank statements drift apart, and the finance team ends up matching transactions by hand in spreadsheets.

Fraud that outpaces static rules

Rules written for last year’s patterns miss new scams — and when customers are tricked into sending money, payment firms can be required to reimburse them.

Consumer Duty needs evidence

The FCA expects firms to monitor and evidence good customer outcomes. That takes journeys and management information designed for it, not a quarterly spreadsheet.

Partners with narrow APIs

Core banking platforms, card processors and banking-as-a-service partners expose limited interfaces, so every new feature starts as an integration question.

Audit trails added too late

When approvals and overrides are not recorded from the start, answering a complaint, an auditor or the regulator means digging through emails and chat logs.

AI use cases

AI that fits a regulated firm.

Bounded, logged jobs where AI reads, sorts and drafts. Decisions that affect customers stay with your people and your policies.

Onboarding teams

KYC document extraction

Read passports, driving licences, bank statements and proof of address, extract the fields and flag mismatches with the application for an analyst to check.

Fraud and financial crime

Alert triage

Summarise the context behind each fraud or monitoring alert — account history, device, payee — so analysts clear false positives quickly and spend their time on real risk.

Complaints teams

Complaint classification

Categorise complaints, spot possible signs of vulnerability, track response deadlines and group root causes for Consumer Duty reporting. A person confirms each one.

Customer service

Assistant with guardrails

Answer questions about fees, limits and payments from approved content only, never give financial advice, and hand disputes, complaints and signs of vulnerability to a person.

Credit and lending

Transaction categorisation

Sort Open Banking transactions into income and spending categories so underwriters can review affordability faster. The lending decision follows your credit policy.

Marketing and compliance

Financial promotion pre-checks

Check draft adverts, emails and app copy against your financial promotions checklist before compliance review — as preparation, never as a replacement for it.

Technology & integration

Technology for software that moves money.

We build on the published APIs of your banking partner, payment provider and identity checks — and design for the day one of them is slow or unavailable.

Payments

StripeCard tokenisationPay-by-bank via Open BankingPayouts, refunds and disputes

Identity and onboarding

Document and liveness checksSanctions and PEP screeningCompanies House APIBank account verification

Applications

React Native and FlutterNext.js and ReactNode.js and TypeScriptJava and Spring Boot

Ledgers and data

PostgreSQLDouble-entry ledger designIdempotent APIs and webhooksReconciliation jobs

Hosting and operations

AWS, including UK regionsDocker and KubernetesSecrets and key managementMonitoring and alerting

AI and analytics

Document extraction and OCRLLMs with guardrailsAnomaly detection modelsEvaluation sets and audit logs

Security & data

How we build around money and personal data.

The engineering practices we apply by default in financial products — and the evidence your risk and compliance teams will ask for.

Card data kept out of your systems

Hosted payment fields and tokens instead of card numbers, which keeps your PCI DSS scope as small as it can be.

Strong authentication

Multi-factor login, device binding and step-up checks for sensitive actions, designed around Strong Customer Authentication, with 3-D Secure handled by your card provider.

Maker-checker approvals

Four-eyes approval for payouts, limit changes and manual overrides, enforced by the software rather than a process document.

Append-only audit trails

Sensitive actions and decisions logged with who, what and when in append-only records — ready for a complaint, an audit or a request from the regulator.

Encryption and secrets

Data encrypted in transit and at rest, secrets in a managed vault, keys rotated, and production access limited, time-boxed and logged.

Evidence for supplier oversight

Data-flow diagrams, control descriptions and support for penetration testing, so you can oversee us as a supplier and answer your own auditors.

We are a software development company, not a compliance consultancy, law firm or regulator. We build to the requirements your compliance, risk and legal teams set — Consumer Duty, PCI DSS scope, safeguarding, record-keeping — and provide the technical evidence they ask for. Regulatory permissions and compliance sign-off stay with your firm.

How we work

How a fintech project runs with us.

Seven stages, the same on every project. The length of each one changes with the work; skipping one never saves time for long.

  1. 01

    Discovery

    Alongside users and goals, we map the regulatory perimeter early: which firm holds which permissions, where money and personal data flow, which partners are involved and who signs off.

    Scope with permissions and data flows mapped

  2. 02

    Strategy

    We agree what to build first and what to leave out, pick the engagement model, and set milestones with a budget range in pounds.

    Scoped first release and estimate

  3. 03

    UX & architecture

    Journeys designed for good outcomes — clear fees and terms, friction only where it protects customers, support for people in vulnerable circumstances — alongside the ledger and integration design.

    Tested journeys and a ledger design

  4. 04

    Development

    Two-week sprints with a demo at the end of each, code review on every change, and a staging environment your team can use.

    Working software every sprint

  5. 05

    Testing

    Reconciliation tests against real settlement files, failure-path tests for retries, duplicates and late webhooks, and security testing before anything handles live money.

    Test evidence your risk team can review

  6. 06

    Launch

    A staged rollout behind feature flags and limits, with monitoring, runbooks and a rollback plan agreed with your operations and compliance teams.

    A controlled launch with runbooks

  7. 07

    Optimisation & support

    After launch we fix, measure and improve — a support retainer, a roadmap of next features, or a clean handover to your own team.

    Support plan or handover

FAQs

Questions we get asked.

Straight answers on scope, cost, timelines and how we work. If yours is not here, ask us directly.

Ask us a question

Who holds the FCA permissions — you or us?

You do, or the authorised partner you work with, such as a bank or e-money institution that provides accounts and cards under its own permissions. We are a software supplier, not the regulated firm: the regulated firm stays accountable for the service and oversees us as a supplier, and we build to its requirements and give it the evidence it needs.

Can you integrate Open Banking into our product?

Yes. Most firms connect through an authorised Open Banking provider rather than holding AISP or PISP permissions themselves. We integrate the provider’s APIs for account data and pay-by-bank payments, design the consent, reconnection and failed-payment journeys, and keep that layer separate so adding providers or Open Finance data later is a contained change.

How do you keep our PCI DSS scope small?

By keeping card data away from your systems: payment fields hosted by your provider, such as Stripe, and tokens stored instead of card numbers. That keeps your PCI DSS scope as small as it can be. Your acquirer or QSA confirms which assessment applies — we give them the technical detail.

Can you build KYC, KYB and AML onboarding?

Yes. We integrate identity and screening providers for document, liveness, address and sanctions checks, and use the Companies House API to pull company, officer and PSC data for business customers. Your MLRO sets the risk rules; the software applies them consistently and stores the evidence against each customer.

How does Consumer Duty affect the software we build?

It shapes design decisions: clear fees and terms, no unnecessary barriers to cancelling, complaining or switching, and support for customers in vulnerable circumstances. We also build the outcomes data and reporting you need to monitor and evidence all of that. Whether outcomes are good enough is judged by your board and compliance team.

Can we use AI in a regulated financial firm?

Yes, for bounded tasks with human oversight: reading documents, triaging alerts, classifying complaints and drafting replies. We avoid fully automated decisions with significant effects on customers, such as declining credit, unless your firm has designed the safeguards UK data protection law requires — and we log inputs and outputs so every result can be explained.

Will you go through our supplier due diligence?

Yes. Tell us at the start what your outsourcing and operational resilience policies require from a supplier, and we will say plainly what we can provide and what we cannot. Because you own the code, IP, documentation and cloud accounts, exit is simpler: the product stays with you if the relationship ends.

How much does fintech software development cost?

It depends on scope, integrations and the evidence your compliance team needs. A discovery sprint starts from £2,000; the first release is then quoted as a fixed-price project with milestone billing. Provider fees — identity checks, Open Banking, card issuing — are separate running costs, and we estimate them up front.

Start a project

Building or fixing a financial product?

Tell us what the product does, which partners hold the permissions and which systems are involved. We will come back with the questions that matter — including the compliance ones — and a realistic first step.

  1. 1A senior engineer reads your brief within one working day, and replies with questions or a first view.
  2. 2A 30-minute call to understand the goal, constraints and what good looks like — no sales script.
  3. 3A written proposal with scope, milestones, team and a GBP estimate you can take to your board.

Techsleight Labs is a trading name of Krapton IT Consultancy.

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