Industry
Software engineering for Fintech & Financial Services
Fintech is where a software mistake becomes a regulatory event. We build financial products that survive audit, penetration testing and a real payments incident, and we are honest that the compliance burden, not the code, is usually the hard part.
Why the domain matters
Fintech is software that moves, holds, lends against or reasons about other people’s money, and that single fact changes everything about how it has to be built. A bug in most products is an inconvenience. A bug in a payments flow is a customer whose rent did not clear, a duplicated debit, or a reconciliation break that takes a week to unwind. The engineering standards that feel like over-engineering elsewhere (idempotency, immutable ledgers, exhaustive audit trails, defence in depth), are the baseline here, not the polish.
The defining constraint is not technical, it is regulatory. Before a line of code matters, you have to answer questions that shape the entire architecture: are you handling client money, and if so who safeguards it? Are you touching card data, and if so how do you stay out of PCI DSS scope? Are you a regulated entity, or are you building on top of someone who is? These are not decisions you retrofit. They determine your data model, your third-party stack, your timelines and your cost base. We have seen more fintech projects stall on compliance ambiguity than on any hard engineering problem.
We are engineers, not a law firm and not compliance consultants, and we will say so plainly. We build the software; your regulatory permissions, your safeguarding arrangements and your financial and legal advice come from people qualified to give them. What we do bring is the discipline to build systems that hold up when the FCA, an auditor or an attacker starts asking hard questions, and the honesty to tell you when the sensible path is to build on a licensed provider rather than try to become one yourself. Because we operate what we build, we live with the reconciliation reports and the incident pages, which is exactly why we take the boring parts seriously.
The challenges in fintech & financial services
The compliance burden defines the architecture
In most sectors, regulation is a checklist you satisfy near the end. In fintech it is the first architectural decision. Whether you safeguard funds, whether card data ever touches your systems, whether you hold a permission or borrow one: each answer forces different data models, different vendors and different timelines. Teams that treat compliance as a later phase routinely have to rebuild core flows once the real requirements land.
Money movement must be correct, not just fast
Payments and ledgers do not tolerate the “eventually consistent, good enough” patterns common elsewhere. A retried request must not double-charge. A failed transfer must leave the ledger in a known state. A balance must reconcile to the penny against the provider’s records every single day. Getting this wrong does not degrade the experience. It loses money and breaks trust, often silently until reconciliation surfaces it weeks later.
You are a top-tier attack target from day one
Fintech sits alongside banking as one of the most attacked categories on the internet, and attackers do not wait for you to reach scale. Credential stuffing, account takeover, synthetic identities, first-party fraud and API abuse arrive early. Security cannot be a hardening sprint before launch; it has to be in the authentication design, the fraud controls and the data handling from the first commit.
Third-party dependence is unavoidable and risky
Almost every fintech runs on a stack of providers. Banking-as-a-Service, payment rails, KYC/AML vendors, card issuers, Open Banking aggregators. That is the right model, but it means their outages are your outages, their rate limits are your ceiling, and their onboarding timelines gate your launch. Systems that assume these dependencies are always available and always fast fail badly in production.
Consumer Duty raises the bar on the whole product
The FCA’s Consumer Duty pushes the obligation beyond “was it compliant” to “did it deliver good outcomes”. That reaches into product decisions software usually treats as neutral: how clearly fees are shown, whether vulnerable customers can navigate a flow, whether a cancellation is as easy as a sign-up. Engineering has to make these things demonstrable, not just present.
Auditability has to be built in, not bolted on
When something goes wrong (a disputed transaction, a suspected fraud, a regulatory query), you must be able to reconstruct exactly what happened, when, and on whose authority. Retrofitting that level of audit trail into a system that logged loosely is painful and often incomplete. It has to be a first-class concern in the data model, or you will be reconstructing history from fragments during an incident.
What we build for fintech & financial services
The systems this sector most often needs, built by engineers who understand the domain, not just the code.
Digital banking and current-account apps
Consumer and business banking experiences built on a Banking-as-a-Service or licensed core provider, account opening, balances, transfers, cards and statements. We handle the onboarding journey, SCA-compliant authentication, real-time transaction feeds and the daily reconciliation against the provider’s ledger, so the numbers your customers see always match the numbers of record.
Payment products and money movement
Products built on Faster Payments, SEPA, Open Banking payment initiation and the card networks. We design idempotent payment flows, webhook handling that survives retries and out-of-order delivery, status reconciliation, and the failure handling that decides what happens when a rail times out mid-transfer. This is the work that conceptually sits behind any dedicated payments service page.
Lending and credit platforms
Origination, decisioning, servicing and collections for consumer or SME lending. We build the application journey, integrate affordability and credit-reference data, wire in the decisioning logic your risk team owns, and model the loan ledger (repayments, arrears, interest accrual), with the accuracy that both customers and auditors expect.
Wealth, investment and financial dashboards
Tools that aggregate accounts, present holdings, and help people understand their money, portfolio views, Open Banking account aggregation, cash-flow analysis and reporting. We build the data pipelines and the interface; the regulated advice, where any is given, stays firmly with authorised parties. We build tools that inform, not systems that quietly stray into giving investment advice.
Embedded finance and platform APIs
Finance surfaced inside a non-financial product, payments, accounts or lending embedded in a marketplace, SaaS platform or vertical app, typically on top of a BaaS partner. We build the integration layer, the developer-facing APIs, and the isolation that keeps each embedded partner’s data and money movement cleanly separated.
RegTech and compliance tooling
Software that makes regulatory obligations tractable, transaction monitoring, KYC/AML case management, sanctions and PEP screening workflows, suspicious-activity reporting and Consumer Duty evidencing. We build the tooling and the audit trails; the rules, thresholds and regulatory judgement remain with your compliance function.
Where we help
Onboarding with KYC/AML that does not haemorrhage users
A sign-up flow that satisfies identity verification, sanctions screening and anti-money-laundering checks while still letting genuine customers through. We integrate the KYC/AML vendor, orchestrate the step-up checks, and design the journey so friction lands where risk is, not on everyone, conceptually the work behind any dedicated KYC or identity service.
A payment flow that is correct under failure
A transfer that behaves sensibly when the network drops mid-request, when the rail returns an ambiguous status, or when a customer taps “pay” twice. Idempotency keys, a state machine per payment, reconciliation against the provider, and clear rules for what a “pending” payment can and cannot become.
Fraud and account-takeover defence
Real-time signals feeding risk decisions at the moments that matter, login, device change, new payee, unusual transaction. We build the instrumentation, wire in fraud-detection and behavioural signals, and design the step-up authentication so that the right challenge fires without turning every action into a friction point.
Daily reconciliation and financial reporting
The unglamorous engine every serious fintech needs: an automated daily reconciliation between your ledger and every provider you depend on, with breaks flagged, explained and chased. When finance and compliance can trust the numbers without a manual spreadsheet pass, a whole class of month-end pain disappears.
How we build for fintech
We start with the regulatory and money-movement questions, not the UI. Who holds the licence? Where does client money sit, and who safeguards it? Does card data ever enter scope? What is the source of truth for every balance? These answers shape the architecture, so we settle them before committing to a design, and if they are not settled, that is the first problem we help you surface.
We push you toward building on licensed providers wherever it is sensible. For most fintechs, becoming an authorised entity (an EMI, a lender, a payment institution), is a multi-year, capital-heavy commitment that is rarely the right first move. Building on a BaaS or authorised partner lets you ship a real product while someone else carries the permission and the safeguarding. We will tell you honestly when the partner model fits and when your ambitions genuinely require your own permissions.
We treat the ledger and the money-movement core as the crown jewels. Immutable, append-only records; double-entry accounting where it belongs; idempotency on every mutating operation; and reconciliation as a first-class daily process rather than an afterthought. The flashy parts of a fintech get the attention, but this core is what determines whether the business can be trusted with money.
We build for audit from the first commit. Every material action carries who did it, when, on whose authority and against what prior state. That discipline costs a little up front and saves enormous pain during disputes, fraud investigations and regulatory queries, because you can reconstruct exactly what happened instead of arguing from partial logs.
Because we operate what we build, we design for the incident, not just the demo. Runbooks for a rail outage, alerting on reconciliation breaks, clear degradation when a provider is down, and a rehearsed answer to “a payment is stuck: now what?”. The teams who skip this find out the hard way, usually at the worst possible time.
The regulatory landscape
UK fintech operates under the FCA, and the central question for any new product is whether you need your own authorisation or can operate under an authorised partner or as an agent. Holding a permission (as an Electronic Money Institution, payment institution, consumer-credit lender or investment firm), brings capital requirements, ongoing reporting and direct supervision. Operating on top of a licensed provider shifts much of that burden to them. This is a strategic decision with major engineering consequences, and it belongs at the very start.
PSD2 and UK Open Banking govern access to payment accounts and the initiation of payments. If you are aggregating accounts or initiating payments, you are working within a defined regulatory and technical framework (regulated APIs, consent flows and specific security requirements), not a free-for-all. The consent and re-consent journeys in particular are easy to get wrong in ways that break both compliance and the customer experience.
Strong Customer Authentication (SCA) requires multi-factor authentication for a broad range of payments and account access, with a specific set of exemptions. Getting SCA right is a genuine engineering exercise: applying the correct exemptions, handling step-up cleanly, and not degrading the experience for every legitimate customer in the name of security. Done badly, it either fails compliance or drives customers away.
KYC and AML obligations (identity verification, sanctions and PEP screening, transaction monitoring and suspicious-activity reporting), are non-negotiable and shape onboarding and ongoing monitoring alike. If you handle client money, safeguarding requirements dictate how those funds are held and kept separate, and the software has to make that separation demonstrable. And the Consumer Duty overlays all of it, holding you to good customer outcomes rather than mere technical compliance.
To be completely clear: we are the engineering partner, not the source of your regulatory permissions or your legal and compliance advice. We build software that implements the controls your compliance function and advisers define, and that stands up to scrutiny. Deciding which permissions you need, and confirming that a given design meets your obligations, is work for qualified people, and we will always point you to them rather than pretend otherwise.
The fintech integration stack
Open Banking APIs are the backbone of account aggregation and payment initiation in the UK. Working with them well means handling consent lifecycles, token refresh, per-bank quirks and the reality that coverage and reliability vary across providers. An aggregator smooths some of this, but the underlying variability still leaks through and has to be handled gracefully.
Payment rails each have their own semantics, timings and failure modes. Faster Payments is near-instant but has limits and cut-offs; SEPA covers euro transfers with its own scheme rules; card networks bring authorisation, capture, settlement, chargebacks and PCI obligations. Building on these well means respecting each rail’s actual behaviour rather than pretending they are interchangeable pipes.
Banking-as-a-Service providers supply the regulated core (accounts, cards, ledgers), that most fintechs build on rather than replicate. The integration quality here largely determines your product quality: webhook reliability, reconciliation against their records, sensible handling of their rate limits and maintenance windows, and a clear model of what is your source of truth versus theirs.
KYC/AML and identity vendors handle verification, screening and monitoring. These integrations shape onboarding conversion directly, so the orchestration: when to check, how to step up, how to handle referrals and manual review, matters as much as the vendor choice itself.
Underneath sits the core-banking or ledger system, whether a provider’s or your own. This is the system of record for money, and every other integration ultimately has to reconcile back to it. We treat reconciliation between your ledger and each external system as a permanent, automated process, because when these records silently diverge, you have a financial problem, not just a technical one.
Security for financial software
Fintech is a top-tier target, and the threat is broad: credential stuffing and account takeover, card and payment fraud, synthetic identities, first-party fraud, API abuse and social engineering. Security here is not a launch-gate hardening exercise: it is a design constraint present from the first commit, in the authentication model, the fraud controls and the way every piece of sensitive data is handled.
The single most important card-data decision is to avoid holding raw card data at all. We design so that primary account numbers never touch your systems, using tokenisation and the payment provider’s vaulting so that what you store is a token, not a card. This is the difference between a manageable PCI DSS scope and a costly, high-risk one, and the honest advice is almost always to stay out of scope wherever the architecture allows.
Encryption is a baseline, not a feature: everything in transit over TLS, sensitive data encrypted at rest, and disciplined key management. Beyond encryption, tokenisation and strict data minimisation limit the blast radius of any breach: you cannot leak what you never stored.
Fraud detection has to operate in real time at the decision points that matter, login, device change, adding a payee, an unusual transaction. That means the right instrumentation, behavioural and device signals feeding risk decisions, and step-up authentication that fires proportionately rather than punishing every customer for the actions of a few.
Around all of this sits operational security: least-privilege access, comprehensive and tamper-evident audit logging, incident response you have actually rehearsed, and regular penetration testing. Because we operate what we build, these are not documents we hand over and forget. They are the controls we rely on ourselves when something goes wrong.
What changes
Money movement you can trust
Payment and ledger flows that are idempotent, reconciled daily against every provider, and correct under failure, so duplicated debits, silent balance drift and week-long reconciliation breaks stop being a recurring source of incidents and lost money.
A defensible compliance and audit position
Systems built to be examined: complete audit trails, demonstrable SCA and safeguarding behaviour, and evidence for Consumer Duty outcomes. When an auditor, the FCA or a dispute asks what happened, you can show it rather than reconstruct it.
A realistic path to launch
A clear-eyed decision on building atop licensed providers versus pursuing your own permissions, with an architecture that matches. That usually means shipping a real, compliant product far sooner, and spending your capital on the product rather than on a licence you did not need yet.
What we build for fintech & financial services
From a first platform to modernising what you already run. The disciplines this sector draws on most.
How we deliver
- 01
Discover
We map the system, the constraints and the business it serves, including the parts nobody documented.
Architecture brief
- 02
Architect
Decisions get made, written down and defended before a line of production code exists.
Decision records
- 03
Build
Short cycles against working software. You see progress in the product, not in a status deck.
Shipping increments
- 04
Operate
Monitoring, incident response and iteration. The system is alive, so the engagement is too.
Runbooks & SLOs
Building something for fintech & financial services?
Tell us the problem and the constraints you are working under. A senior engineer will give you a straight view on what it would take, and say so plainly if we are not the right team for it.
Technologies we work in
Chosen per problem, not per fashion. A selection of the stack we most often reach for.
Why teams in fintech & financial services choose us
Senior engineers who have felt the reconciliation break
Fintech punishes juniors-run-the-project staffing. Our people are senior engineers who understand idempotency, ledgers, audit trails and the specific ways money-movement systems fail, because they have operated them, not just read about them.
We operate what we build
We do not hand over a payments system and walk away from the pager. Living with the reconciliation reports and the incident pages is exactly why we take the unglamorous correctness and observability work seriously from the start.
Honest about the compliance reality
We will tell you plainly when you should build on a licensed provider instead of chasing your own permission, when a design puts you needlessly into PCI scope, and where the real timeline risk sits. We would rather lose a fortnight of billing than build you something that fails audit.
Engineering that stays in its lane
We are the engineering partner, not your compliance function or your law firm. We implement the controls your qualified advisers define and build software that survives scrutiny, and we are explicit about where our responsibility ends and theirs begins.
Related sectors
Adjacent sectors we also know.
Common questions
Do we need to become FCA authorised, or can we build on a partner?
That is a strategic decision with major engineering consequences, and it depends on what you are doing with money. Many fintechs (especially at first), are best served building on a Banking-as-a-Service or authorised partner that holds the permission and safeguards funds, letting you ship a real product without a multi-year authorisation process. Some products genuinely require your own permissions. We will give you an honest engineering view of the trade-offs, but the definitive answer on which permissions you need comes from your regulatory advisers, not from us.
Will you handle our regulatory compliance and licensing?
No, and we are deliberate about that boundary. We are engineers. We build software that implements the controls your compliance function and advisers define, and that stands up to audit, penetration testing and regulatory scrutiny. Your permissions, your safeguarding arrangements, and your financial and legal advice come from people qualified to provide them. We will happily build to their requirements and point you toward them where you do not yet have them.
How do you keep us out of PCI DSS scope?
The core principle is that raw card data should never touch your systems. We design so that primary account numbers are captured and vaulted by your payment provider, and what you store and handle is a token, not a card. That keeps your PCI scope minimal and manageable rather than costly and high-risk. Where a design genuinely requires broader scope we will say so clearly, but the honest default is to architect card handling so you stay out of scope wherever possible.
How do you make sure payments are not duplicated or lost?
Correctness under failure is a first-class design goal, not an afterthought. We use idempotency keys so a retried request cannot double-charge, model each payment as a state machine with well-defined transitions, handle webhooks that arrive late or out of order, and reconcile against the provider’s records daily so any discrepancy is caught and explained rather than discovered weeks later. The aim is that a dropped connection or a double tap leaves the ledger in a known, correct state every time.
Can you integrate our KYC/AML, Open Banking and payment providers?
Yes. That integration layer is much of the work in a modern fintech. We build against KYC/AML and identity vendors, Open Banking APIs, payment rails such as Faster Payments and SEPA, card networks and Banking-as-a-Service cores, and we treat reconciliation between your ledger and each external system as a permanent automated process. The orchestration: when to run checks, how to handle referrals, how to degrade when a provider is down, usually matters as much as the vendor choice, and that is where careful engineering earns its keep.
Building for fintech & financial services?
Tell us what the system has to do and what it cannot get wrong. A senior engineer reads it, and if fintech & financial services is not a domain we know well enough to be useful in, we will say so rather than learn it on your budget.
- 01A senior engineer reads it. Not a form queue, and not an account manager.
- 02We reply either with questions or with a straight answer that we are not the right fit.
- 03If it looks like a fit, a technical call with the person who would actually run the delivery.
- 04Then scope, effort and risk in writing, before anyone signs anything.