How Much Does Custom Software Development Cost in the UK?

Why most software agencies won't give you a number

Ask a typical software agency what a project costs and you'll usually get "it depends" followed by a request to book a call. That's not always evasion — cost genuinely does depend on scope, and a number given before any real conversation is a guess dressed up as a quote (we've written about why we don't do that ourselves). But "it depends" without any further detail isn't useful to someone trying to work out whether custom software is even in their budget range before picking up the phone.

So here are real, honest ranges — the same bands we actually use internally when scoping a project — broken down by the type of system, so you have something concrete to work from before a first call.

Custom CRM: roughly $5,500 – $12,000

A CRM built around your actual sales or operational process — role-based portals, a pipeline that matches how you sell rather than a generic template, and reporting on the metrics you actually care about. This is usually the smallest of the categories below because the core pattern (record, pipeline, dashboard) is well understood; the cost variance comes from how many distinct user types the system needs to serve and how much of your existing data needs migrating in. Typical timeline: 4-6 weeks.

Multi-Tenant SaaS Platform: roughly $8,000 – $16,000

A subscription product with tenant isolation, recurring billing, team workspaces and role-based access control. This costs more than a CRM because a SaaS platform has to be built to serve multiple separate customers securely from one codebase — a fundamentally different architecture from a single-business internal tool. Typical timeline: 6-8 weeks.

Two-Sided or Three-Sided Marketplace: roughly $9,500 – $18,000

As we've written about in marketplace architecture decisions, a working marketplace is genuinely three products — customer, provider, and admin — which is why this category runs higher than a single-application build. The cost driver here is usually payment flow complexity (upfront vs. on-completion) and whether proof-of-work capture (photos, signatures, GPS) is required. Typical timeline: 6-10 weeks.

ERP / HRM / Operations Platform: roughly $9,000 – $19,000

Systems that unify staff scheduling, payroll exports, inventory or resource tracking, and management reporting into one operational engine. This is typically the highest-cost category because these systems tend to touch the most distinct workflows inside a business at once — scheduling, financial data, compliance records — each of which needs its own careful handling. Typical timeline: 6-9 weeks.

What actually moves you within a range

Every project we scope lands somewhere in its category's range rather than at a fixed number, and the same few factors decide where:

How many distinct user types the system serves. A CRM with one type of internal user costs less than one serving internal staff, external partners, and customers, because role-based access control done properly is a real design decision, not a checkbox.

Whether you're migrating existing data. Moving years of spreadsheet history into a new system cleanly takes real time, and it's often underestimated in a rough mental budget.

Third-party integrations. Payment processing, WhatsApp/SMS notifications, accounting software exports — each one is a real piece of work, not a toggle switch, and the number of integrations you need shifts the estimate meaningfully.

How much of the design is decided already. A clear brief with an existing brand and defined workflows scopes faster than "we're not sure yet what we want this to do."

What these numbers don't include

These ranges cover the build itself — architecture, development, testing, and launch. They typically don't include ongoing hosting costs (usually modest — Vercel, Supabase and similar cloud services scale with usage, often starting under $50/month for a new system), and they don't include a support retainer beyond the standard post-launch warranty period, if you want ongoing feature development after launch.

Why we publish this at all

Most agencies treat pricing as something to reveal only after a sales call, which we think mostly serves the agency, not the buyer. Publishing real ranges means you can rule custom software in or out of consideration in five minutes, rather than losing a week to an unproductive back-and-forth. If your project fits inside one of these bands, it's worth a real conversation. If it's clearly outside what these numbers suggest — much bigger or much smaller — we'll tell you that honestly on the call too.

Want an actual number for your specific project, not just a range? [Book a 30-minute call](/contact) — we'll give you a real proposal after we've talked, not before.