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Build · Digital Products

Identity & payments integration

Secure sign-in, national and federated identity, and payment flows integrated to the standards regulators and auditors expect.

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The challenge

Identity and payments are the two places where a digital service is most likely to be attacked and most likely to be audited. They are also where users abandon a journey if the experience is clumsy.

Organisations often integrate identity providers, payment gateways and strong customer authentication under deadline pressure, leaving token handling, session management and reconciliation as afterthoughts. The weaknesses surface later as fraud, account takeover or failed audits.

We integrate identity and payment services with the security controls designed in from the start, the user journey kept as simple as the risk allows, and reconciliation and evidence built for the auditor.

Our method

How the work is done.

  1. 01

    Risk and journey assessment

    Define assurance levels, fraud risks and the user journeys affected, and agree where friction is justified.

  2. 02

    Protocol and provider design

    Select and design the OpenID Connect, SAML or payment gateway integrations, including token lifetimes, scopes and key management.

  3. 03

    Secure implementation

    Build sign-in, consent, session and payment flows with server-side token handling, idempotent payment calls and webhook verification.

  4. 04

    Reconciliation and evidence

    Automated reconciliation between your ledger and the provider, with audit logs that support dispute handling and compliance review.

  5. 05

    Testing and certification support

    Security testing of the flows and support through any provider or scheme certification process.

Deliverables

What you receive.

  • Identity and payment architecture with sequence diagrams for each flow
  • Implemented sign-in, session, consent and payment integrations
  • Key and secret management design
  • Reconciliation jobs and exception reports
  • Audit logging specification and implementation
  • Security test report covering authentication and payment flows
  • Evidence pack to support PCI DSS scoping and assessment

Engagement options

Ways to buy it.

  1. 01

    Integration review

    Assessment of existing identity or payment flows against current standards, with a prioritised fix list.

    2–4 weeks
  2. 02

    Integration build

    Design and implementation of new identity or payment capabilities, through to production.

    2–5 months
  3. 03

    Identity consolidation

    Consolidating multiple user stores and sign-in methods onto a single identity platform with staged migration.

    3–6 months

Standards

Frameworks we work to.

  • OpenID Connect
  • OAuth 2.0 Security Best Current Practice
  • SAML 2.0
  • NIST SP 800-63
  • PCI DSS v4.0
  • FIDO2 and WebAuthn
  • EMV 3-D Secure

Questions

What buyers ask us.

Can you reduce our PCI DSS scope?

Often, yes. Using hosted payment fields or redirects keeps card data out of your systems, which narrows what has to be assessed. We design for this from the outset.

Do you support passwordless sign-in?

Yes. We implement passkeys and other FIDO2 methods alongside fallback routes for users who cannot use them.

How do you handle failed or duplicate payments?

Payment calls are idempotent, webhooks are verified and replay-safe, and reconciliation flags any mismatch between your records and the provider's for review.

Will we be tied to one identity or payment provider?

We isolate provider-specific code behind your own interfaces so a change of provider is a contained piece of work rather than a rewrite.

Related services

Often delivered together.

Build

API & systems integration

Connecting core systems, legacy databases and third-party services safely, observably and without fragile point-to-point links.

Secure

Penetration testing

Controlled, evidence-led attacks on your applications, networks and cloud estate, reported in terms your engineers and your board can both act on.

Secure

Governance, risk & compliance

Gap assessments, risk registers, policies and audit readiness against ISO 27001, SOC 2, PCI DSS and NIST CSF, built to be used rather than filed.

Discuss identity & payments integration.

A senior engineer reviews every enquiry and replies within one business day.