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Legal Practice Management Software: Buy vs Build in London (2026)

Mohamed Bah·Fondateur, Kolonell
September 6, 2026
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Legal Practice Management Software: Buy vs Build in London (2026)

Legal Practice Management Software: Buy vs Build in London (2026)

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The verdict in three sentences

For a small firm, an off-the-shelf SaaS (GBP 35-80 per user per month) is unbeatable in the early years. Beyond 12-15 users and with atypical workflows (e-filing, complex fee arrangements, trust accounting), custom becomes profitable over a 4-to-6-year horizon. The real question is not the entry price but the 5-year TCO measured against how well the tool fits your process.

Buy vs build: the true 5-year cost

The classic trap is comparing a monthly subscription to a development quote. You must think in total cost of ownership, licences AND configuration AND the productivity lost to workarounds.

Item (15-lawyer firm)Off-the-shelf (SaaS)Custom build
Initial / setup costGBP 3,000 - 7,000GBP 35,000 - 85,000
Annual subscriptionGBP 9,450 - 21,600GBP 0 (owned)
Hosting + maintenance/yrincludedGBP 3,500 - 8,000
Process customisationlimitedfull
5-year TCO (estimate)GBP 50,250 - 114,000GBP 49,000 - 125,000
Code ownershipnoyes

2026 ballpark: over 5 years the two options cross around 15 users. Below that the SaaS wins; above it, custom amortises its fixed cost.

What custom actually changes

An off-the-shelf tool imposes its screens and logic. Custom follows your value chain: matter opening, conflict check, e-filing, time-based billing, disbursements, partner reporting.

CriterionGeneric SaaSCustom build
Fit to firm process60-75 %95-100 %
Court e-filing integrationvariablenative
Bespoke fields and reportsnoyes
Implementation time2-6 weeks12-20 weeks
Data reversibility / exportvendor-dependentfull
On-demand enhancementsvendor roadmapyou decide

Mini case study

James, managing partner of a 15-lawyer London firm, pays GBP 60 per user per month, i.e. GBP 10,800/yr. Three Excel workarounds cost roughly 6 hours/week of paralegal time billed internally at GBP 22/hr, i.e. GBP 6,864/yr of friction. A custom tool at GBP 65,000, plus GBP 5,500/yr maintenance, removes the friction: over 5 years, GBP 92,500 versus GBP 88,320 for SaaS-with-friction. Beyond year five, custom pulls ahead and it owns a software asset.

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What is the break-even point for custom?

As a 2026 ballpark, it sits around 12 to 15 active users and a 4-to-6-year horizon. Below that, a SaaS at GBP 35-80 per user per month stays cheaper.

Does a custom tool handle court e-filing?

Yes, integration can be native through the relevant APIs. This is precisely where the market is weak: many SaaS products only partially cover these flows.

How long to develop a custom solution?

Budget 12 to 20 weeks for a scope covering matter management, calendar, billing and e-filing. A targeted MVP can ship in 8 to 10 weeks.

What happens to my subscription if I switch SaaS vendors?

You lose functional history and must migrate your data, often at the cost of a limited export. Custom guarantees full reversibility because you own the code and the database.

Can we start on SaaS then move to custom?

Yes, this is a common path: SaaS to validate needs, then a data migration into a proprietary tool once the firm stabilises above 12 users.

Let's scope your project. Tell us about your firm (number of lawyers, e-filing flows, billing model) and we will price buy vs build over 5 years. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.

Tags:#legal practice management#buy vs build#custom legal software#law firm london#software tco#court e-filing#case management#legal tech
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Mohamed Bah

Fondateur, Kolonell

Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.