Fintech engineering that survives audit.
Ship money-moving software without breaking compliance.
We have shipped production fintech for five years — payments, ledgers, brokerage UX, KYC flows, and Stripe integrations that actually reconcile. Sage Ideas builds money-moving software with the boring discipline regulators expect: idempotent webhooks, append-only ledgers, audit trails on every state transition, and SOC 2-ready evidence from day one. You move faster because we have already made the expensive mistakes.
Why Sage Ideas for Fintech
What we solve
The specific operational challenges we've already debugged in the fintech stack.
Webhooks that double-charge customers
Stripe retries on 5xx and network timeouts. Without idempotency keys, deterministic event handlers, and a deduplication store, you will eventually create duplicate ledger entries. We design the boring infrastructure that makes this impossible.
Ledger drift between Stripe and your database
Your application database and Stripe diverge slowly — refunds processed manually, disputes that never make it into your books, fees missing from MRR calculations. We build reconciliation jobs that close the gap nightly and alert before finance notices.
PCI scope creeping into your codebase
Once card data touches one service, your audit boundary explodes. We refactor checkout flows to use Stripe Elements or Hosted Checkout, prove tokenization at the edge, and produce the data-flow diagram your QSA needs.
KYC flows that block legitimate users
Drop-off at identity verification is silently killing your activation. We instrument the funnel, integrate with Persona/Alloy/Stripe Identity, and build manual-review queues that do not require an engineer in the loop for every edge case.
Recommended tiers
Productized engagements ordered by relevance to fintech workloads.
Relevant work
Fintech questions
Can you reduce our PCI scope?
Yes — the goal is almost always SAQ A or SAQ A-EP. We move card capture into Stripe Elements or Hosted Checkout so card data never touches your origin, then produce the network and data-flow diagrams your QSA will request. If you currently take card numbers via a custom form or store anything that looks like a PAN in your database, that is the first thing we change.
How do you handle Stripe webhooks safely?
Every handler is idempotent on Stripe event ID — we store processed event IDs and short-circuit on replay. Handlers are pure functions over the event payload (we re-fetch from the API rather than trust webhook bodies for amounts), wrapped in database transactions so partial failures roll back cleanly. Retries are exponential with a dead-letter queue after N attempts so engineers can inspect rather than data silently disappearing.
Do you know the difference between Stripe Connect, Treasury, and Issuing?
Yes. Connect is for marketplaces and platforms paying out to third parties — Standard, Express, and Custom accounts have different KYC and liability profiles. Treasury is FBO-account banking-as-a-service for paying companies and earning yield. Issuing is for spawning virtual or physical cards. They are often combined (Connect + Issuing for spend management products) and the choice cascades into your compliance posture, so we want to make it deliberately, not by accident.
What does SOC 2 evidence collection look like in practice?
It is mostly automation plus discipline. Drata/Vanta/Secureframe pull evidence from AWS, GitHub, and your HRIS automatically, but they cannot collect what does not exist — so we make sure access reviews happen quarterly with a documented log, deploys are tied to ticketed change management, secrets rotate on a schedule, and incident runbooks have post-mortems attached. The Audit and Operate tiers map directly to the CC-series controls auditors care about most.
Are you our compliance officer or our auditor?
No, and we will say so loudly. We are the engineering team that builds systems your compliance officer and QSA can defend. We work alongside them — we will join calls, answer technical questions, and produce architecture documentation in their preferred format — but the legal sign-off and attestations are theirs to give. If you do not have either yet, we can recommend firms we have worked well with.
Bring us your reconciliation drift, your webhook nightmares, or the SOC 2 deadline that keeps you up at night.
Book a 30-minute discovery call. We'll talk through your fintech stack and tell you directly which engagement — if any — is the right fit.
Book a Discovery Call