Skip to content
Hire us

API Development and Integration Services · United Kingdom Make your systems work together.

API development services for UK businesses: custom REST and GraphQL APIs, third-party integrations and webhooks that move data reliably between your products, partners and internal systems.

Discuss your project

UK-registered company. International engineering team.

01 /

API development for UK businesses.

Every growing UK business ends up with systems that need to talk: the CRM and the accounting package, the website and the warehouse, the booking system and the payment provider, a partner’s platform and yours. Krapton designs and builds APIs and integrations that move data between them reliably, securely and in a way your developers can understand.

We build REST and GraphQL APIs with clear contracts, authentication and rate limits, integrate third-party services such as Stripe, GoCardless, HubSpot, Xero, Sage and Open Banking providers, and handle the difficult parts properly: retries, idempotency, webhooks, partial failures and monitoring.

  • Node.js
  • NestJS
  • Python and FastAPI
  • .NET
  • PostgreSQL
  • REST and GraphQL
  • OpenAPI
  • Message queues
  • AWS and Azure

02 /

Why UK businesses
choose Krapton for API development.

Contracts before code

OpenAPI specifications, versioning and documentation agreed first, so front-end, mobile and partner teams can build against a stable interface.

03 /

What the engagement can include.

Map the systems of record first. Agree how retries, duplicate events, rate limits and partial failures should behave before connecting production data.

  • API contracts, authentication and access controls

  • Third-party integrations and webhook handling

  • Versioning, automated tests and developer documentation

04 /

A clear path
from brief to release.

Four stages, each producing something you can see and decide on. Milestones, acceptance criteria and demonstrations are agreed before we commit.

Our process in detail

  1. 01

    Map the systems of record

    Which system owns each piece of data, how it flows today and where it breaks. Agree the events, entities and edge cases the API must handle.

  2. 02

    Design the contract

    Endpoints, schemas, authentication and error formats written down as an OpenAPI specification and reviewed with everyone who will use it.

  3. 03

    Build and test

    Implementation with automated contract and integration tests, sandbox accounts for third parties and load testing where volume matters.

  4. 04

    Deploy, monitor, document

    Staged rollout, dashboards and alerts for failures and latency, and developer documentation your team and partners can rely on.

05 /

See the work
behind the conversation.

Examples from Krapton’s international portfolio. Each success story describes the work delivered for that project.

Sendora project visual

Fintech / Cross-border Payments

Sendora

Sendora lets users send money internationally with zero transfer fees, spend on a global debit card and build credit from their phone — but the marketing site had to communicate trust, speed and global coverage at a glance, in a category where trust is everything.

Read the success story

06 /

Sectors where this
service does the most.

07 /

Clear scope.
Visible progress.

We agree priorities, responsibilities, milestones and acceptance criteria before delivery. Work remotely with Krapton’s international engineering team through regular reviews and working demonstrations.

What every UK engagement includes

  • A written quote in GBP for an agreed scope
  • Contracts with Krapton IT Consultancy Ltd under the law of England and Wales
  • Working-hours overlap, demos and written updates
  • UK GDPR-aware data handling and hosting choices
  • Code, accounts and documentation in your name

08 /

API development: questions UK buyers ask.

What is the difference between API development and integration?

API development means building an interface to your own system so other software can use it. Integration means connecting existing systems, often through their APIs. Most projects involve both: a small API on your side plus connections to third-party services.

Can you integrate with UK payment and accounting providers?

Yes. We have worked with Stripe, GoCardless and Open Banking providers for payments, and Xero, Sage and QuickBooks for accounting, alongside CRMs, helpdesks and logistics APIs. Where a provider is new to us, we assess its documentation and sandbox before quoting.

How do you make integrations reliable?

Idempotent requests, retries with backoff, queues for asynchronous work, webhook verification and reconciliation checks that compare both systems. Failures are logged and alerted rather than silently dropped.

Do you provide API documentation?

Yes. Every API ships with an OpenAPI specification, generated reference documentation and examples, and the integrations are documented so your team can operate them without us.

How do you secure APIs that handle personal data?

Authentication and scoped authorisation on every endpoint, encryption in transit and at rest, field-level minimisation, rate limits and audit logging. We design with UK GDPR in mind and can support your DPIA where one is required.

09 /

Build the
wider picture.

Related services for the next part of your project.

Let’s talk API development.

Tell us what you want to improve. We’ll help you shape the right scope, team and starting point.

What are you thinking?