connect third party api saas uk

Integrating the right third-party services can be the difference between a SaaS platform that struggles and one that scales. At By Design UK, we specialise in connecting external APIs to custom-built SaaS products — giving UK businesses the automated workflows, real-time data, and joined-up functionality their customers expect from a modern software platform.

What does third-party API integration actually mean for your SaaS?

It means your platform can communicate with external services — payment processors, CRMs, logistics tools, communication platforms, and more — without manual data entry or duplication of effort. Rather than building every feature from scratch, API integration lets your SaaS pull in trusted, proven functionality and serve it seamlessly to your users. Our team at By Design UK architects these connections as part of full SaaS builds priced from £18,000, or as scoped integration work within an existing platform.

Which APIs can be connected to a custom SaaS build?

Almost any API that exposes a public or authenticated endpoint can be integrated. Common examples our UK clients request include Stripe and GoCardless for payments, Twilio for SMS and voice, SendGrid and Mailchimp for email automation, Xero and QuickBooks for accounting, Salesforce and HubSpot for CRM, and specialist data providers relevant to specific industries. Our work on Tackly.co.uk — a live SaaS platform now serving 25 industries — demonstrates how carefully designed API architecture can support diverse workflows at scale without compromising performance or data integrity.

How much does SaaS API integration cost in the UK?

Costs are shaped by the number of APIs, the complexity of the data transformations required, authentication methods (OAuth, API keys, webhooks), and how deeply each service needs to be embedded in the user experience. By Design UK delivers SaaS platform builds — including all API integrations — from £18,000 up to £650,000+ for enterprise-grade solutions. Every project begins with a scoping session so you receive a fixed, transparent quote before any development begins.

Do you provide ongoing API maintenance after launch?

Yes. APIs change — providers deprecate versions, update authentication flows, and alter rate limits. Our SaaS monthly support plans from £797 per month cover API monitoring, version updates, error handling improvements, and proactive alerts if a third-party service causes disruption to your platform. It is the safety net that keeps your product reliable long after go-live.

Why do UK SaaS businesses choose By Design UK?

We are a UK-registered digital development company based at Office 13, 25 Mollison Avenue, Enfield EN3 7LW. Every project is handled by our in-house team — no outsourcing, no handoffs to unknown contractors. Our clients value direct communication, documented architecture, and a delivery process built around commercial outcomes rather than billable hours. Tackly.co.uk stands as evidence that our SaaS builds are production-ready and built to grow.

Frequently Asked Questions