Top 10 API Development and Integration Companies in the UK for 2026

UK businesses rarely commission an API just to connect two internal apps anymore. Banks expose account data to authorized third parties, healthcare suppliers plug into NHS-connected systems, and retailers sync orders with payment providers and marketplaces. Each connection brings its own authentication, consent, and audit requirements. The partner you pick must understand those obligations as well as the code.

Here are the top 10 API development and integration companies in the UK:

• Cleveroad
• Integrella
• Zudu
• Bit Zesty
• Softwire
• Imaginary Cloud
• GoodCore Software
• Digiryte
• Foresight Mobile
• Studio Graphene

Our analyst team began with about 70 UK firms that list integration, API, or modernization work among their services. We then checked each firm's profile, client reviews, and delivered projects across these sources:

• Clutch
• GoodFirms
• DesignRush
• TechBehemoths
• Official company websites

To narrow the pool to 10, every firm had to meet each criterion below. The final mix covers specialist integrators, enterprise consultancies, and product studios, so you can match the vendor type to the project you have in mind:

• An office in the United Kingdom
• Integration or API work shown in services or client reviews
• An average rating of 4.7 or higher from verified clients
• Delivery experience in regulated sectors such as finance, healthcare, or the public sector
• A custom development model rather than a packaged product
• Clear post-launch support

The table below compares the 10 shortlisted companies by their UK presence, API development and integration services, and industry expertise.

The table shows how wide the spread is, from specialist healthcare integrators to enterprise consultancies and product studios. The profiles show where each firm fits and which buyer it serves best.

• Founded: 2011
• Offices: Manchester (United Kingdom), Claymont, Delaware (United States)
• Hourly Rate: $50–$99/hr
• Industry Expertise: Healthcare, FinTech, logistics, eCommerce, education
• Reviews: 75+ reviews on Clutch, average rating 4.9/5
• Services: Custom API development, third-party API integration, API design and architecture, cloud API development

With 15+ years in software development, Cleveroad designs custom APIs and connects products to the third-party services they depend on. Our engineers build REST and GraphQL APIs for client-facing products and use gRPC for fast service-to-service traffic. Each API ships with OAuth 2.0 and JWT authentication and rate limiting, while versioning keeps partner integrations stable through updates. On the integration side, we connect CRMs such as Salesforce and HubSpot and identity providers such as Auth0 and Okta. As an AWS Select Tier Partner, our team runs cloud-hosted APIs on managed AWS services.

Every one of those connections moves data, and for UK companies much of that data is regulated. When an API carries customer profiles, we apply UK GDPR principles at the design stage: each endpoint exposes only the fields its consumer needs, and logs leave out personal data. Card payments follow the same logic. Our PCI DSS delivery experience keeps raw card numbers inside tokenised gateways such as Stripe and away from your servers. Our ISO/IEC 27001:2013 certification for information security management governs how we store API keys and control access to personal data.

Once partners depend on your API, how you release changes matters as much as security. Our ISO 9001:2015 certification for quality management covers how we review and release API changes, so updates go live and existing integrations keep working. Clients rate that consistency highly, and Cleveroad holds 75+ reviews on Clutch with a 4.9/5 average. Clutch named us a Global Leader in Fall 2025 and included Cleveroad in its Top 1000 list for 2025.

Best for UK companies that need payment, CRM, or partner integrations delivered with UK GDPR-aware security, ongoing API maintenance, and a Manchester team that works UK hours.

Consumer apps show how much this integration work matters. A consumer app rarely runs on its own backend alone. It relies on several third-party APIs at once, such as payments, maps, push notifications, and email, and each one has its own authentication and data format. Our engineers treat that integration layer as part of the core product, because the app only works when every connected service exchanges data correctly.

El Tab, a London drinks subscription service, shows how many integrations even a compact product needs. Subscribers pay for access to drinks offers at partner pubs and get a weekly push notification with the venue’s name and location. To support that model, we delivered a cross-platform Flutter app and a web admin dashboard for managing users, partners, and tabs.

Payments run through Stripe, Apple Pay, and Google Pay. Google Maps shows venue locations, and Firebase and Socket.IO deliver notifications and real-time updates. AWS SES handles email, and Swagger documentation covers the whole API.

See what Oliver Carew, founder of El Tab, says about the collaboration and why he recommends Cleveroad as a reliable development partner for integration-heavy apps.

• Founded: 2007
• Offices: London (United Kingdom), Ahmedabad (India)
• Hourly Rate: $25–$49/hr
• Industry Expertise: Healthcare, financial services, education
• Reviews: 4 reviews on Clutch, average rating 5.0/5
• Services: Healthcare system integration, integration as a service, data integration, product development

Integrella develops secure, real-time integrations that connect products to healthcare systems, including urgent and emergency care pathways. The team also handles system migrations and offers integration as a service for ongoing connectivity. Best for health-tech suppliers that need to connect with NHS-connected systems.

• Founded: 2014
• Offices: Edinburgh (United Kingdom)
• Hourly Rate: Undisclosed
• Industry Expertise: Financial services, healthcare, public sector, energy
• Reviews: 23 reviews on Clutch, average rating 5.0/5
• Services: Systems integration, legacy modernisation, platform engineering, custom software

Zudu delivers systems integration and legacy modernisation for regulated organisations, with public-sector work such as ScotRail and NHS Scotland projects. Platform engineering and custom software development complete the service mix. Best for public bodies and regulated firms modernising ageing systems.

• Founded: 2009
• Offices: London (United Kingdom)
• Hourly Rate: $150–$199/hr
• Industry Expertise: Medical, government, consumer products, eCommerce
• Reviews: 11 reviews on Clutch, average rating 4.8/5
• Services: Custom web applications, API upgrades and integrations, application support and maintenance, AI automation

Bit Zesty rewrites legacy applications with upgraded REST APIs and syncs commerce data with ERP systems, for example from Shopify to an ERP. Support and maintenance contracts keep the same team on the product after release. Best for organisations with long-lived Ruby on Rails or government-facing apps that need ongoing support.

• Founded: 2000
• Offices: London, Manchester, Cambridge (United Kingdom)
• Hourly Rate: $100–$149/hr
• Industry Expertise: Media, financial services, government
• Reviews: 11 reviews on Clutch, average rating 4.7/5
• Services: Custom software development, systems engineering and modernisation, data platforms, AI development

Softwire provides enterprise software engineering and modernization across large media, finance, and public-sector estates. Its systems engineering and data platform work suits organizations whose integrations sit inside complex legacy environments. Best for enterprises modernizing core platforms with a fully UK-based team.

• Founded: 2010
• Offices: London (United Kingdom), Lisbon and Coimbra (Portugal)
• Hourly Rate: $50–$99/hr
• Industry Expertise: Financial services, legal, medical, retail
• Reviews: 35 reviews on Clutch, average rating 4.9/5
• Services: AI-enabled custom development, cloud-native platform engineering, nearshore engineering teams, product design

Imaginary Cloud offers cloud-native platform engineering and custom development delivered by nearshore teams in Portugal. That model keeps rates in the $50–$99/hr band while clients keep a UK point of contact. Best for fintech and legaltech companies that want UK oversight with nearshore rates.

• Founded: 2005
• Offices: London (United Kingdom), Karachi (Pakistan)
• Hourly Rate: $25–$49/hr
• Industry Expertise: Business services, education, medical, financial services
• Reviews: 31 reviews on Clutch, average rating 5.0/5
• Services: Bespoke software development, platform integration with existing systems, SaaS development, software project takeover

GoodCore Software designs bespoke platforms that integrate with a client's existing systems. The team also takes over stalled projects from other vendors and carries development forward. Best for SMEs that need an integrated platform on a controlled budget.

• Founded: 2016
• Offices: Salford (United Kingdom)
• Hourly Rate: $50–$99/hr
• Industry Expertise: Financial services, medical, retail, eCommerce
• Reviews: 51 reviews on Clutch, average rating 4.9/5
• Services: Web application development, data engineering, cloud consulting, AI/ML development

Digiryte develops web platforms and data engineering pipelines, backed by cloud consulting and technical audits. With 51 Clutch reviews, it has one of the deepest review records on this list. Best for scale-ups that need data pipelines and backend work alongside product development.

• Founded: 2017
• Offices: Manchester, Birmingham, London (United Kingdom)
• Hourly Rate: $50–$99/hr
• Industry Expertise: Sports, consumer products, financial services
• Reviews: 14 reviews on Clutch, average rating 5.0/5
• Services: Mobile app development (Flutter, native), API integration and backend development, AI integration, app rescue

Foresight Mobile develops mobile apps with API integration and backend development, plus SDK work and AI model integrations. The team also rescues troubled apps that other vendors left unfinished. Best for brands whose integration needs centre on a mobile product.

• Founded: 2014
• Offices: London (United Kingdom), Lisbon (Portugal)
• Hourly Rate: $50–$99/hr
• Industry Expertise: Business services, consumer products, financial services
• Reviews: 25 reviews on Clutch, average rating 4.7/5
• Services: AI product development, custom software development, mobile app development, product design

Studio Graphene handles AI-native product strategy, design, and development for new digital products. Integrations come as part of that product work rather than as a standalone service. Best for startups and corporate innovation teams launching a new product with integrations around it.

Strong profiles still need a stress test. These seven warning signs tend to surface in the first calls and proposals, long before a contract is signed.

A vendor that jumps into code without an OpenAPI spec or a contract review will change endpoints mid-project. Your frontend and partner teams then rework their side every sprint.

Vague answers about authentication, secrets management, or rate limiting mean security will be patched in later. Ask exactly how tokens are issued, stored, and revoked.

A reliable partner knows where personal data is stored, logged, and processed, including in error logs and backups. If the answer is simply "in the cloud", keep asking.

Without one, every release can break the partner integrations that still rely on the old contract.

Contract tests, sandbox environments, and load tests belong in the plan from the start. A team that also provides DevOps services can wire those checks into CI/CD and monitor the API after release.

Quick connectors bolted onto old databases work until the first schema change. Look for a vendor that proposes an architecture, or legacy software modernisation where the old system can't expose data safely.

If the contract is vague on IP and the proposal skips documentation, you depend on the vendor for every future change. Make the specs, repository, and credentials named deliverables.

This shortlist spans specialist healthcare integrators, regulated-sector modernisers, enterprise consultancies, and product studios, with rates from $25–$49/hr to $150–$199/hr. We compiled it from Clutch, GoodFirms, DesignRush, TechBehemoths, and official company websites, so every firm has a verifiable public record.

Pick two or three firms whose "Best for" lines match your project and run the seven red flags against each proposal. Compare written answers rather than pitch decks. If you plan to move your API layer to the cloud, our engineers can design it with you as part of cloud application development.