Then Stripe replayed a webhook during a brief outage. Eleven customers got charged twice. The reconciler caught it the next morning, refunds went out in 18 hours, the Slack channel did not calm down. The CEO asked the obvious question: “Why is our payments code retrying without idempotency keys in 2026?”
Service Stripe integration services · Connect + Tax + Billing · UK
Stripe integration services with zero refund chaos. and no double-charges.
Stripe integration services for UK SaaS, fintech, marketplaces, and D2C. We wire Subscriptions, Tax, Connect, Identity, and Issuing across GBP, USD, and EUR — with idempotent webhooks, a nightly reconciler, and an audit log finance can actually read.
38Stripe integrations shipped
0double-charge incidents
100%webhook idempotency
Why CTOs sign with us
You don’t need another Stripe team. You need engineers who’ve shipped 38 Stripe integrations and watched what breaks at scale.
Stripe integration services aren’t a checkout button. They’re idempotent webhooks, a reconciler against your ledger, and an audit log finance can query. We build the part that holds at month-end.
“Take your hand-rolled Stripe codebase and rebuild it for production behind a flag. Double charges stop, month-end goes from a week to minutes.”
001
0+
Stripe integrations shipped to production for UK teams since 2019.
002
0%
Webhook idempotency, so a replayed event never charges a customer twice.
003
0
Double-charge incidents across every production deploy we’ve run.
The CTO this page is for11 double-charges · refunds by hand · 0
Marcus’s SaaS used Stripe. The product was good. The webhook handler had no idempotency.
The product wasn’t the problem. The Stripe integration was. Refunds were processed by hand. Month-end took a week. Finance dreaded it. There was no audit log they could query, and no nightly check that Stripe and the database agreed.
We rebuilt the Stripe integration with idempotency keys on every handler, a nightly reconciler comparing Stripe events to the DB, and an audit log finance could read. Shipped over four weeks. Double charges stopped. This page is for CTOs who recognise themselves in that paragraph.
The Stripe pain. The day-1 architecture answer.
Each one is the difference between a Stripe integration finance trusts and one they email support about every month-end.
- 01
“Stripe retried a webhook. We charged the customer twice.”
Idempotency key, dedupe table, DLQ. An idempotency key on every webhook handler. Dedupe at the edge. Failures to a DLQ. Replay-safe by design. Double-charge architecturally impossible.
- 02
“Month-end refunds done by hand. Three customers refunded twice.”
Idempotent refund flow with reconciler. An audit log per refund. A double-refund caught before it commits. Month-end reconciliation in minutes, not the dread of a full week.
- 03
“We started selling to the EU. VAT confusion. Tax filings late.”
Stripe Tax + OSS + IOSS wired. Stripe Tax with OSS for B2C EU. IOSS for low-value imports. A documentation pack for quarterly returns. Cross-border tax stops being a finance ticket.
- 04
“Marketplace platform. A refund got pulled from a supplier balance with no notice.”
Destination charges, platform-controlled refunds. Supplier liability documented per transaction. A dispute resolution flow that’s audit-logged. Express, Custom, and Standard Connect chosen per buyer.
- 05
“EU SCA challenges drop 14% of conversion. The CFO bleeds.”
3DS2 with an exemption strategy. Low-value, MIT, and trusted-beneficiary exemptions reasoned per route. Strong Customer Authentication that’s audit-defendable. EU conversion recovers to UK levels.
- 06
“11% of subscribers churn at the first failed payment. No retry strategy.”
Smart Retries, dunning, self-serve portal. Smart Retries enabled. Dunning emails staged via Customer.io. A self-serve update-card flow. Failed-payment churn typically halves.
- 07
“A customer upgraded mid-cycle. Proration was wrong by £87. The CSM refunded by hand.”
Stripe Billing proration with Test Clocks. Stripe Billing handles proration. Test Clocks validate every billing scenario in CI before it ships. Manual proration ends.
- 08
“Month-end. The Stripe dashboard and our ledger differ by £1,400. Nobody can find why.”
Internal ledger reconciled nightly, Stripe Sigma. The ledger reconciled to Stripe every night. Stripe Sigma queries the source of truth. A discrepancy caught within 24 hours, never at month-end.
WHAT KEEPS A STRIPE INTEGRATION ALIVE PAST THE FIRST RETRY STORM
Four things that carry payments from launch to a clean month-end
The engineering that separates a checkout that works on a demo from a Stripe integration your finance team trusts and your acquirer’s diligence team walks through without flinching.
Webhook idempotency, 100%
Every event carries an idempotency key, a dedupe table sits at the edge, failures go to a DLQ. Replay-safe by design. A double-charge isn’t prevented by policy, it’s architecturally impossible. Zero across 38 Stripe integrations shipped.
A reconciler that matches reality
A nightly reconciler checks every Stripe event against your database. No drift, no surprise at month-end. A £1,400 discrepancy is caught within 24 hours, never on the last day of the quarter. Your finance team trusts the numbers from month one.
Cross-border tax that satisfies HMRC
Stripe Tax with OSS for B2C EU, IOSS for low-value imports, VAT calculated per region. The documentation pack for quarterly returns ships with the build. Cross-border tax stops being a finance ticket and starts being a non-event.
Observability from the first deploy
Sentry, Datadog APM, and structured logs on every webhook handler, wired before launch. When a payment fails you see why, when a customer disputes a charge you have the trace. You know which flow is breaking on day one, not after the first angry email.
The stack we ship every Stripe build on.
Stripe’s own product surface for payments. Node plus Express runtime. The hiring pool that means your next engineer reads the integration on day one and follows it.
T1
What every Stripe build runs on
Stripe-firstStripe Payments + BillingStripe ConnectStripe TaxStripe IdentityStripe RadarStripe SigmaStripe IssuingStripe Test ClocksStripe CLINode + Python SDKsStripe ElementsSentry + Datadog
T2
When your Stripe brief calls for it
reach when neededPythonJavaGoGraphQLtRPCDrizzle / Prisma
T3
The infrastructure for scale
AWS-defaultAWSCloudFrontAWS LambdaAWS RDS / AuroraMongoDB AtlasRedisInngest / Trigger.devTerraformGitHub Actions
The numbers finance trusts
Real outcomes from the Stripe integrations we’ve shipped, measured at month-end, not on a demo.
11→0
Double-charges per quarter, after
Why is our payments code retrying without idempotency keys in 2026?” That question started the rebuild. Four weeks later the double charges stopped for good.
Results
Marcus’s Stripe integration,
Marcus’s Stripe integration,
after the rebuild, in numbers
We rebuilt a marketplace Connect integration with idempotent webhooks, destination charges, a reconciler against the internal ledger, and Test Clocks in CI. A ten-week sprint for a UK B2B SaaS with 1,800 customers.
Payments
110
Double-charges per quarter
100%
Webhook idempotency
Finance
1wk12m
Month-end reconciliation
Nightly
Ledger reconciled
Track record
38
Stripe integrations since 2019
0
Peak-load outages in 2025
STRIPE SERVICE AREAS
Where we go deep on Stripe
The five Stripe surfaces we’ve shipped enough times that we don’t Google the edge cases.
SERVICE
(01)
Subscriptions & Billing
Stripe Billing handles proration, seats, and plan changes. Test Clocks validate every billing scenario in CI before it ships, so a mid-cycle upgrade never gets refunded by hand.
Stripe Billing
Proration
Test Clocks
Dunning
Subscriptions & Billing
SERVICE
(02)
Connect Marketplaces
Express, Custom, or Standard Connect chosen per buyer. Destination charges with platform-controlled refunds and supplier liability documented per transaction.
Destination Charges
Split Payouts
Platform Liability
Dispute Flow
Connect Marketplaces
SERVICE
(03)
Webhooks & Idempotency
An idempotency key on every handler, a dedupe table at the edge, a DLQ for failures. A replayed webhook returns the original response rather than charging again.
Idempotency Keys
Dedupe Table
DLQ
Replay-safe
Webhooks & Idempotency
SERVICE
(04)
SCA & 3DS
3DS2 with low-value, MIT, and trusted-beneficiary exemptions reasoned per route. Strong Customer Authentication that’s audit-defendable, so EU conversion recovers to UK levels.
3DS2
Exemptions
SCA
EU Conversion
SCA & 3DS
SERVICE
(05)
Reconciliation
An internal ledger reconciled to Stripe every night, with Stripe Sigma querying the source of truth. A discrepancy is caught within 24 hours, never at month-end.
Nightly Reconciler
Stripe Sigma
Audit Log
Ledger
Reconciliation
What CTOs actually ask before signing
Pain-first, soft-second.
Stripe integration services from us run a £25-85K typical band, fixed scope, with the 5-day audit at £8K. The audit hands you a line-item GBP quote before you commit to a build, so you’re never anchoring on a guess. The spread you’ve been quoted elsewhere is usually the difference between a checkout button and a reconciled, idempotent integration. We price the second one.
Yes. We’ve done it for UK clients in 2025. Your existing backend (Rails, Django, .NET, Java, Go) stays. We build the Stripe layer with typed contracts, idempotent webhooks, and a reconciler against your data. Output: a senior-grade Stripe integration without rebuilding your backend.
An idempotency key on every webhook handler, a dedupe table at the edge, a DLQ for failures, and a nightly reconciler that compares Stripe events to your database. A replayed webhook returns the original response rather than charging again. Across 38 Stripe integrations shipped, zero double-charge incidents in production. It’s architecture, not policy.
Stripe Tax with OSS for B2C EU sales, IOSS for low-value imports, VAT calculated per region. The documentation pack for your quarterly returns ships with the build. Cross-border tax stops being a finance ticket and starts being a non-event your accountant signs off in an afternoon.
30-day walk-away both ways. Milestone billing 25/25/25/25. UK VAT registered, listed on Companies House, shipping since 2019. You’re never more than four weeks at risk of paying for nothing.
Every Stripe integration project has two senior engineers paired, not one. Every decision goes into an ADR the same day. Mohit reviews every PR. Two handovers in seven years, both inside 48 hours, neither client noticed.
Yes. Express, Custom, or Standard Connect chosen per buyer, destination charges with platform-controlled refunds, supplier liability documented per transaction, and a dispute resolution flow that’s audit-logged. A refund never gets pulled from a supplier balance without a record of why.
Yes, with 14 days’ notice. Engineers move to other projects. Spend pauses. Resume with 14 days’ notice. No cancellation fee.
In context
What it looks like shipped.
stripe integration, in context — the dashboards, flows and components your team actually ships, reviews and maintains.
One paragraph. That’s it.
Tell us what your Stripe integration needs to do, who’s paying through it, and where the friction is now. Mohit replies inside 24 hours: a clear yes, a clear no, or the one question that decides it.
What happens after the email lands
- < 24h
A personal reply.
Yes, no, or the deciding question. Straight to your inbox.
- Week 1
Stripe architecture drafted.
Idempotency, dunning, SCA, tax, ledger, refund policy. Signed scope.
- Wk 4
Double charges stop.
Idempotent webhooks live, reconciler running nightly, month-end in minutes.