Your London firm pays for SaaS and then pays people to make up for what it can't do
Custom software development in London typically runs £60k to £200k over 4 to 8 months. You build custom when your competitive process, the way you actually run client work, has been bent to fit generic SaaS instead of the software fitting you. For a London agency or fintech, the signal is when you're hiring people specifically to do the work your software can't, and that headcount scales with revenue.
You assembled an operation from best-of-breed SaaS, and on paper it's modern. In practice, the gaps between tools are filled by your people. The way your firm runs a client engagement, the specific sequence of scoping, resourcing, time-tracking, billing, and reconciliation that is genuinely your operation, doesn't exist in any one product, so it lives in the heads and spreadsheets of your team. Generic SaaS gives you 80% and charges you for the other 20% in salaries.
That's a quiet, expensive tax. Every new client adds manual steps. Every process improvement means another integration or another workaround. The London firms that pull ahead stop renting a generic approximation of their workflow and build the 20% that is actually theirs, the part competitors can't copy because it's not on a pricing page anywhere.
- Your core process lives in spreadsheets and people's heads because no SaaS models it
- You're hiring to bridge tool gaps and that cost scales with revenue
- Your differentiating workflow is the thing generic software keeps approximating badly
- Integration sprawl is itself becoming the maintenance burden
- Your workflow is genuinely standard and SaaS covers it without workarounds
- Headcount isn't scaling with revenue because the manual glue is minimal
- You're early enough that requirements are still moving weekly
- No competitive advantage lives in how you run the process; speed of setup matters more
- Your differentiating workflow becomes a system instead of tribal knowledge and spreadsheets
- Revenue can grow without the linear headcount growth generic SaaS forces on you
- Process improvements ship as features rather than yet another integration workaround
- One source of truth replaces the gaps your people currently fill by hand
- You own software that competitors can't buy, because it encodes how you actually operate
- Higher up-front investment than another SaaS subscription, with payback measured in quarters not weeks
- You own maintenance, security, and uptime that the SaaS vendor previously handled
- Build the wrong abstraction and you've hard-coded a process you later need to change
- If your workflow is genuinely standard, generic SaaS is cheaper and you should keep it
Custom Software pricing in London: the real numbers
| Project scope | Typical cost | Timeline |
|---|---|---|
| Custom workflow platform for a London services firm | £90k to £160k | 5 to 7 months |
| Full bespoke operations system replacing SaaS sprawl | £140k to £200k | 6 to 8 months |
| Targeted custom module filling the critical SaaS gap | £60k to £100k | 4 to 5 months |
The features that matter for London
What we build under custom software in London
The engagements London teams bring us most often: systems integration, microservices, database design, bespoke software development, SaaS development and web application development.
Exactly what you get
Software that encodes the part of your operation that is genuinely yours: the scoping, resourcing, time-tracking, billing, and reconciliation sequence that currently lives in spreadsheets and your team's heads. The manual steps your people perform to bridge SaaS gaps become a system. Your CRM, time-tracker, and accounting feed one flow. And the workflow that differentiates your London firm becomes an asset you own rather than an approximation you rent.
How to choose a developer in London
Choose a partner who spends the first sessions mapping your actual process, not pitching a stack. The whole value of custom software is encoding your real workflow, so a team that doesn't deeply understand it will build the wrong thing expensively. Insist on a paid discovery phase and a clear view of which 20% genuinely warrants building versus what should stay in SaaS. Connect the build to your CRM, internal tools, and business intelligence dashboard plans so it becomes the spine of your operation rather than another silo.
From kickoff to launch: the schedule
- !They start with technology, not your workflow; ask them to map your engagement process first
- !No plan to replace manual glue, only to add another tool; ask how headcount stops scaling
- !They over-promise a system that does everything; ask which 20% is actually worth building
- !No audit or access design; ask how they'd handle a client due-diligence request
- !Fixed quote before discovery; ask for a paid discovery phase to de-risk scope
Most London teams pricing custom software end up comparing notes on website, inventory management, warehouse management too; the systems share one data spine.
Rohan advises mid-market and enterprise teams on ERP, CRM and custom software, and has led delivery on dozens of business-software builds.
Writes for Digital Heroes, shipping business software for 2,000+ brands across 55+ countries since 2017.
Frequently asked questions
How do I know custom software is worth it?
The clearest signal is headcount scaling with revenue because people are bridging tool gaps. If adding clients means adding admin staff to make your SaaS cohere, custom software that encodes the workflow usually pays back within a few quarters.
Should we replace all our SaaS?
Rarely. The best builds keep SaaS where it's genuinely good and replace only the 20% that is your differentiating workflow, the part no product models well. Replacing everything is expensive and usually unnecessary.
What's the risk of building the wrong thing?
The main risk is hard-coding a process you later need to change. A good London partner mitigates this with a paid discovery phase and an extensible architecture, so process changes ship as features rather than forcing a rebuild.