Building a multi-tenant SaaS platform is one of the most technically demanding projects in software development. Getting tenant isolation, billing, permissions and scalability right the first time is what separates products that grow from products that stall under their first hundred customers. By Design UK is a UK-based software development agency that specialises in exactly this: fixed-price, AI-accelerated multi-tenant SaaS builds, delivered with full source code ownership handed back to you at the end of the project.
We sit deliberately between a freelancer and a traditional agency. You get the speed, personal attention and fair pricing of an independent developer, combined with the process, testing discipline and reliability of a proper engineering team. No black-box quotes, no disappearing contractors, no six-figure agency retainers for a straightforward MVP.
A true multi-tenant SaaS platform needs to serve many customer organisations from a single codebase and infrastructure layer, while keeping their data, billing and user access completely separate. That typically includes:
We’ve built and continue to operate this exact kind of infrastructure ourselves. Tackly.co.uk is our own live multi-toolkit SaaS platform, running in production with real users and real tenants today. It’s not a case study written after the fact — it’s proof we build the same class of software we sell, and that we understand the operational realities of running a SaaS product, not just shipping one.
Multi-tenant SaaS builds through our SaaS development service generally range from £18,000 to £650,000+, depending on scope. A lean MVP with core tenant isolation, subscription billing and a single core workflow sits toward the lower end of that range. Platforms with complex permissioning, integrations, custom reporting, or enterprise compliance requirements move toward the upper end. Every project is quoted as a fixed price before work begins, based on a detailed scoping session — not an hourly estimate that creeps upward as development progresses.
AI-accelerated development is central to how we hit these price points without cutting corners. We use AI tooling across scaffolding, testing and code review to compress the timeline of routine engineering work, while our senior developers focus on architecture decisions, security and the details that determine whether a multi-tenant system holds up under real usage. The result is agency-grade output at a price closer to freelance rates, with none of the reliability risk of a single contractor.
Most businesses building a SaaS product end up choosing between two flawed options. Freelancers are often cheaper and fast to start, but projects stall when they take on other clients, disappear mid-build, or leave you with undocumented code you can’t hand to anyone else. Traditional agencies bring more structure, but that usually comes with opaque day-rate pricing, slow decision-making layers, and contracts that quietly retain rights over your codebase or lock you into ongoing dependency.
By Design UK exists for the businesses stuck between those two options. You get a fixed price agreed upfront, a UK-based team you can actually reach, and full, unrestricted ownership of your source code the moment the project is delivered. There’s no vendor lock-in and no ambiguity about who owns what — it’s your platform, your codebase, your IP.
A multi-tenant SaaS platform is never really “finished” — new tenants bring new edge cases, and infrastructure needs monitoring as usage scales. Our SaaS support plans start from £797/month and cover monitoring, bug fixes, security patching and incremental feature work, so your platform stays stable as your customer base grows. If your roadmap also includes a storefront or Shopify-based product alongside your SaaS platform, our Shopify development services range from £499 to £18,999, with support from £299/month.
Every engagement starts with a conversation about your product, your tenants, and your growth plans, not a generic questionnaire. You can learn more about how we work on our about page, or get in touch directly via our contact page to discuss scope and a fixed quote for your platform.
Multi-tenant means the platform serves multiple separate customer organisations from a single shared codebase and infrastructure, with each tenant’s data, users and settings kept isolated. Multi-user simply means several people can log into one account — it doesn’t imply that separation between organisations.
Yes. Full source code ownership transfers to you on delivery for every project we build, with no licensing fees, retained rights, or ongoing dependency on By Design UK to keep operating your platform.
Timelines depend on scope, but AI-accelerated development typically allows us to deliver an MVP faster than a traditional agency process, while more complex enterprise-grade platforms take longer to account for integrations, compliance and testing.
Yes. Tackly.co.uk is our own multi-toolkit SaaS platform, built and operated by By Design UK, and serves as direct evidence of our technical capability with real, in-production multi-tenant infrastructure.
By Design UK, Office 13, 25 Mollison Avenue, Enfield, EN3 7LW. Email info@bydesignuk.co.uk to discuss your multi-tenant SaaS build.
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