API integration services

A new provider, partner or client becomes revenue only when the API integration runs in production, mapped to your data model and accepted by the counterparty. Until then the deal sits in a backlog and the account waits, while the sales team explains the delay.

Most of this work is in the regulated layer: KYC, payment gateways, credit bureaus, open banking, lending and reporting, and the partner APIs between a platform and its enterprise clients. The shape changes from one integration to the next. The unit of delivery does not change: one working API integration, owned end to end.

Pulling your own engineers onto that work is expensive in a way that does not show up on an invoice. They come off the product roadmap, the feature they were building slips, and the integration still competes with everything else for their attention. We take the integration as a whole piece of work so your team stays on the roadmap.

A successful HTTP call is not a finished integration. In a regulated flow, the difference shows up when the counterparty changes, when a call fails halfway, and when an auditor asks what happened six months later.

Every integration we deliver includes:

• Idempotent operations, so a retry never creates a duplicate payment or a duplicate customer.
• Retry, backoff and circuit-breaker behaviour for transient counterparty failures.
• Structured logging and correlation IDs, so support can trace one transaction across providers.
• Schema validation on every payload, with clear errors when a contract drifts.
• Monitoring on the integration's own targets, separate from generic infrastructure alerts.
• A runbook your operations team can read at three in the morning, not a wiki page nobody updates.

When one connection is the blocker, the integration unblock sprint takes it from stuck to live in weeks. When the next ten integrations look alike, the reusable integration layer makes each one cheaper than the last. For the platform around the integrations, see financial software development.

Most fintech provider integrations are REST with webhooks, and we add idempotency keys, signed-webhook verification and retry semantics as a baseline rather than an option. Where a counterparty exposes gRPC or a streaming interface, we use it when the latency budget needs it.

Behind the connection, we lean on message queues and event streams so a slow provider cannot back-pressure your core flows. And we treat the long tail of file-based exchange, ISO 20022, SWIFT messages and scheduled file drops, as a first-class integration with the same monitoring and audit trail as a live API, because in banking those formats are not going away.

Most integration work is bought in one of three shapes, and we will tell you which fits on the first call. A single connection with a clear specification and stable counterparty access is usually a fixed-price piece, scoped and quoted against a defined acceptance test, so you know the cost and the finish line before we start.

Where the scope is still moving, a discovery phase on time and material is the honest answer. Provider documentation is often wrong, sandbox behaviour rarely matches production, and a short paid discovery surfaces those gaps before they become a fixed-price dispute. We convert to a fixed scope once the unknowns are closed.

When the goal is not one connection but a repeatable capability, an outcome-based engagement around the reusable integration layer ties the commercial terms to integrations shipped rather than hours billed. Whichever shape you pick, the integration code, tests and runbooks land in your repositories, so you are never tied to us to run what we built.

For the consolidation shape, see payment platform consolidation.

Not every integration is greenfield. Some of the most consequential integration work is replacing a provider that is being retired, repriced or has become a risk - a KYC vendor, a payment gateway, a credit data source - while the flows it serves keep running. The new adapter is the easy part. The hard part is moving live traffic across without losing a transaction, a consent or an onboarding that is mid-flight. We treat a provider switch as a migration, not a rebuild:

• Parallel running, with the old and new integrations processing the same traffic and their outputs reconciled.
• Phased cutover in slices, so a fault touches a fraction of volume.
• A rehearsed rollback path, so reverting is a routine action rather than an incident.
• Decommissioning in scope: the old adapter, its credentials and its monitoring removed, not left behind.

The end state matters as much as the cutover. You finish with one integration where there used to be two, a reconciliation both sides have signed off, and no dormant credentials or half-retired code waiting to surprise the next audit. Done properly, the only people who know the switch happened are the ones who planned it.

In a regulated platform, the vendor is part of the attack surface, and your security team is right to treat us that way. We expect to be onboarded through your access process, not around it: named individuals, least-privilege accounts issued by you, your devices or your virtual environment where policy requires it, and access that you can revoke in one step the day the engagement ends.

Integration work touches real customer data only where it must, and by default it does not. Development and testing run on masked or synthetic data; production personal data stays in production, behind your controls. When a defect can only be reproduced with live data, the investigation happens inside your environment, under your access policy, and is logged like any other production access.

Everything we change reaches production through your review and release process, so the audit trail of who changed what is the same one your own team produces. When we leave, offboarding is part of the handover: accounts closed, credentials rotated, and nothing of yours retained on our side. Your compliance team can vet that arrangement before kick-off - we would rather have the conversation first than mid-build.

On the compliance questions a regulated buyer's procurement asks, in short:

• DORA: where it applies to your scope, we support the outsourcing register entry, the audit and exit clauses, and the exit drills run before any switch-over.
• PCI DSS: the certification is the platform's, not ours - we build to keep your PCI scope tight and flag the boundaries early, so an integration never puts your certification at risk.
• Subprocessors: we work inside your environment on accounts you issue, so we do not introduce our own subprocessors for your data.