Custom fintech software development for founders building regulated financial products.

Fintech software development looks easier than it is. In 2026 the surface area expanded.

A few years ago, building a fintech product meant integrating Stripe, adding KYC via a vendor like Persona or Alloy, and shipping. The regulatory bar has moved since then — and the technical bar has moved with it.

On the regulatory side: state-level financial regulations have multiplied. NYDFS Part 500 cybersecurity rules apply to anyone holding a New York DFS license; California's CCPA/CPRA and several other states' equivalents add data-residency layers; GLBA's Safeguards Rule was updated in 2023 with new specific technical controls; and the federal AML/BSA program has aggressively expanded beneficial-ownership reporting requirements under FinCEN. PCI-DSS 4.0 reached its mandatory compliance deadline in 2025 with stricter requirements on multi-factor authentication, scripts on payment pages, and continuous compliance monitoring (not annual audit). Most early-stage fintechs we meet are between two and four years behind their current regulatory obligations.

On the technical side: AI is reshaping which parts of fintech are tractable. Document-heavy workflows that previously required armies of analysts — KYC review, due diligence packages, audit workpapers, loan underwriting documents — are being rebuilt around LLMs that can reason over structured and unstructured inputs together. Real-time fraud detection moved from rule-based engines toward model-driven scoring with explainable decisions. But these AI-driven workflows have to coexist with the deterministic guarantees regulators and auditors expect. "AI in fintech" is more about boundary design than model selection.

The teams who win the next two years in fintech are the ones who can move at AI-era pace while staying audit-grade — exactly the tightrope we've been walking with clients on the regulated side of financial services for the past few years.

PCI-DSS architecture is one decision, repeated everywhere.

The single highest-leverage architectural decision in any payment-handling fintech product is PCI scope reduction. Every server, every database, every developer laptop, every backup that touches cardholder data falls into PCI scope. Auditors validate every system in scope. Every system in scope requires controls, logging, vulnerability management, and recurring evidence.

The architectural goal isn't to be "PCI-DSS compliant" as a binary state. It's to keep the in-scope footprint as small as humanly possible, so the cost of compliance scales sub-linearly with the size of the product.

What PCI-DSS-compliant architecture actually looks like

Common patterns in the platforms we ship:

• Tokenization at the edge. Card data is captured inside a payment processor's iframe or SDK and exchanged immediately for a token. Application servers never see raw PAN data. This single decision removes 80%+ of services from PCI scope.
• Explicit PCI envelope. Services that can touch cardholder data are explicitly tagged. Cross-envelope calls go through documented APIs with field-level audit logging. This is enforced at the network layer (security groups, service mesh policies), not just by developer discipline.
• HSM-backed key custody. Encryption keys live in a hardware security module or KMS with documented rotation, access controls, and split-knowledge / dual-control policies for production access.
• Continuous compliance evidence. PCI-DSS 4.0 shifted from "annual audit" to "continuous compliance" for many controls. We design logging and monitoring so the evidence an auditor needs is produced automatically, not retrofitted before an assessment.
• Strong customer authentication. MFA on anything that touches cardholder data. Risk-based step-up authentication for high-value transactions. Session-binding for sensitive operations.
• Webhook security as a first-class concern. Every inbound webhook from a payment processor has signature verification, replay protection, and idempotent handling. Webhooks that don't verify signatures are a vulnerability class auditors flag.
• Backup and DR that's tested. Backups encrypted, separately stored, with restore tested at least annually. The distinction between "we have backups" and "we have tested restore" is the distinction between passing and failing an audit.

Beyond PCI — SOC 2, SOX, NYDFS, AML, GDPR/CCPA

PCI is just one regulatory regime. Most fintech products live under several at once. We help design control architectures that satisfy multiple regimes from the same set of technical controls — so SOC 2 Type II evidence, NYDFS Part 500 requirements, and PCI-DSS controls don't each demand their own unique implementation. A well-designed audit log doubles as evidence for all three.

For public-company fintech subsidiaries, SOX ITGC controls apply to systems that touch financial reporting. We've shipped inside that context for our enterprise clients — Citi, Dun & Bradstreet, Morgan Stanley — where the bar for change management, access review, and segregation of duties is set by PCAOB-aware auditors, not internal preference.

AI in fintech: speed without losing audit posture

The question we got in 2025 was "can we use OpenAI for our fintech product?" In 2026, founders ask "how do I add AI features to my fintech without breaking my SOC 2 or making my next audit a nightmare?"

The answer comes down to three architectural choices.

1. The data boundary on the model

What data does the model see, where does inference run, what gets logged? Options span from "nothing customer-data ever reaches the model" (de-identify or tokenize before inference) to "model runs inside the BAA / DPA envelope on Azure OpenAI, AWS Bedrock, or dedicated infrastructure." Each option has implications for which features you can build, which vendors you're locked into, and what changes if you switch providers.

Our default architecture isolates AI inference into a dedicated service with a clear input/output contract. The rest of the application doesn't know it's calling an LLM — it calls a structured service that happens to be model-backed today. This means we can swap providers, run multiple in parallel for A/B comparison, or fall back to deterministic logic when models are unavailable.

2. Auditability of every AI decision

Regulators and auditors will eventually ask "why did this AI-generated decision happen." Every LLM call that influences a customer-facing outcome — fraud flag, credit decision, AML alert, account closure — needs a complete audit record: input (or its hash if sensitive), model version, prompt template version, output, downstream effect, and the human who reviewed it if applicable. This audit log is also your dataset for measuring model quality drift over time.

3. Human-in-the-loop where stakes are high

A model that approves a $1,000 loan without human review is a regulatory liability. A model that drafts a SAR for a compliance officer to review and file is an efficiency multiplier. The design decision is which workflows can run autonomously and which require a human. We tend to bias toward assistive AI — the model proposes, a qualified human disposes — for any decision that touches a customer's money or eligibility.

What we've shipped

Audit Hero is the canonical example: AI-powered extraction and analysis of large trust reports, financial statements, and audit workpapers. It cut a workflow that took analysts days down to minutes — but with structured audit trails, citation back to source documents, and human review gates at the decision points that matter. The audit firm using it has confidence in their workpapers because the AI doesn't replace judgment; it makes judgment fast.

Tools we work with

OpenAI via Azure OpenAI (BAA / DPA coverage), Anthropic Claude via AWS Bedrock or direct enterprise access, open-source models hosted on dedicated infrastructure for the most sensitive workloads, LangChain and the Model Context Protocol (MCP) for orchestration of multi-step financial workflows. MCP in particular is emerging as a useful pattern for composing AI features inside complex regulated stacks — see our notes on MCP in fintech AI.

How we work on fintech software development engagements

Fintech amplifies the consequences of bad process. A slow-shipping team in a regulated environment doesn't just lose competitive ground; it pays for compliance overhead longer. A fast-shipping team without discipline accumulates audit findings that compound. We try to do both — ship at a pace that founders recognize as fast while never accumulating the kind of debt that surfaces as findings at year two.

1. Discovery and regulatory framing (1-2 weeks)

For new engagements, we start by mapping the regulatory perimeter: which licenses (existing or pending), which data types you'll handle, which states and which payment networks you'll touch, which compliance standards your customers will demand (SOC 2, PCI, vendor risk questionnaires). The output is a written architectural framing — PCI envelope, control mapping, integration plan, BAA / DPA inventory, build sequence. You own it; it survives the engagement.

2. Build sprints with weekly demos

Two-week sprints, Friday demo of working software (not status updates), Monday scope adjustment based on what we just saw. No agile theater — story-point rituals only if the client wants them. Working software every sprint; scope flexes to reality.

3. Compliance evidence as deliverables

PCI-DSS evidence, SOC 2 control narratives, change-management logs, access reviews — produced as work happens, not retrofitted before audits. By the time a customer's security questionnaire arrives, the answers are already in your evidence repo.

4. Embedded code review and security posture

Every PR reviewed; security-relevant changes get a second reviewer. Static analysis, dependency vulnerability scanning, and secret scanning in CI. SAST/DAST for the payment-handling services. We pen-test our own work; we coordinate with external auditors when they test ours.

5. Documentation as code

Architecture decision records, runbooks, BAA inventory, PCI scope diagrams, control mappings — written as code, checked into the repo alongside the systems they describe. Docs that live next to code stay current; docs in Confluence rot inside two quarters.

Geography and accountability

Engineering in Montevideo, Uruguay (Eastern Time aligned), with expansion in Colombia for U.S. West Coast clients. Co-founder David Boucher is U.S.-based, U.S. CPA, and the accountable U.S. principal on every engagement — when something needs an accountable person on the phone, that's him. The combination is rare in nearshore: the staffing economics of LATAM with the procurement-friendly accountability of a U.S. principal.

Fintech software development — frequently asked questions

How much does custom fintech software development cost?

The honest range for a senior nearshore fintech software development team is $25–60/hour blended. Most engagements land between $75,000 and $250,000 over three to six months for new builds (e.g., a fintech mobile app with one banking integration and KYC); multi-year platform engagements scale from there. We have a $25,000 minimum because below that the quality bar isn't sustainable for either side.

How long does a payments integration take?

Six to fourteen weeks is typical for a first-time integration with a major processor (Stripe, Adyen, Worldpay), depending on the depth (one-time pay vs subscription vs split payments vs marketplace), the compliance review timeline on the processor's side, and the maturity of your existing security posture. Banking-as-a-service integrations (Treasury Prime, Unit, etc.) add 4-8 weeks of partner onboarding, BSA program review, and control-attestation work that's outside engineering's control.

Can you build PCI-DSS compliant software?

Yes — see the Compliance architecture section above. Short version: we design payment-handling architectures with explicit PCI scope reduction (tokenization at the edge, network-enforced envelope, HSM-backed key custody, continuous evidence). The architectural goal is to keep PCI scope as small as possible so compliance cost scales sub-linearly.

Do you handle SOC 2 readiness?

We design systems that satisfy SOC 2 Type II controls from inception — access management, change management, monitoring, incident response, encryption. We don't run the audit ourselves; we coordinate with whichever audit firm you choose (we have referral relationships with several for clients who ask). Engineering-side evidence is produced as work happens, not retrofitted before assessment.

Can you integrate with our bank / BaaS provider?

We've shipped integrations with the major banking-as-a-service providers (Treasury Prime, Unit, Synctera, Column), open-banking aggregators (Plaid, MX, Finicity, Yodlee), and direct bank partnerships using ISO 8583, ISO 20022, NACHA, and MT message formats. The integration work itself is usually 4–10 weeks; partner onboarding adds 4–12 weeks on top.

Can you build fintech AI features without breaking compliance?

Yes — see the Fintech AI section. Short version: we architect the data boundary on the model first, isolate AI inference behind a structured service contract, ensure every AI-influenced decision is auditable, and bias toward human-in-the-loop for any decision that touches customer money or eligibility.

What fintech sub-verticals have you shipped?

Embedded finance, payment orchestration, banking infrastructure, risk and compliance systems, KYC/AML workflows, crypto-enabled payments, gaming and casino payment systems, fintech mobile apps, AI-powered audit and document extraction. Lending, wealth management, and insurtech are in our wheelhouse although not on our public case-study list yet.

How do you protect intellectual property?

Mutual NDAs before any commercial conversation. Standard work-for-hire clauses in our MSA. Code lives in your repos, on your accounts, from day one. We don't keep customer code on our infrastructure.

Can you augment our existing team rather than replace it?

Yes. About a third of our engagements are staff augmentation — senior engineers embedded with an existing client team for six to eighteen months, working under the client's engineering leadership. Common for clients with strong in-house teams who need surge capacity or specific fintech regulatory expertise.

Where is your team located?

Engineering in Montevideo, Uruguay (Eastern Time aligned), with a Colombia expansion for U.S. West Coast clients (within 3 hours of PT). Co-founder David Boucher is U.S.-based. U.S. presence in Florida.