Making Build vs. Buy Decisions Without Vendor Marketing

How can a build-versus-buy decision be made independently of vendor marketing?

First, a few business-critical capabilities and exclusion criteria are described, independent of specific products. Purchase and build options then go through the same scenarios for data, roles, exceptions, operation, and exit. A decision is considered robust when evidence and total costs are documented comparably.

Case Study: "Demo Fit"

A demo shows an ideal release process, but not the differing roles of a real-world site. In the scenario test, the vendor must map this special case with a traceable configuration and data export. Simultaneously, an estimate is made of what proportion of an in-house development would truly differentiate the system rather than rely on interchangeable standard features.

Verifiable Commitments

1. Define critical user tasks, mandatory requirements, and acceptable manual work in a product-neutral manner.

2. Evaluate vendor and in-house solutions using the same data, exception, operational, and exit scenarios.

3. Compare evidence, uncertainties, and life cycle costs in a shared decision document.

Shared Cost Horizon

• Proportion of mandatory scenarios that are fulfilled under real-world conditions without unconfirmed vendor assumptions.

• Ratio of internal implementation and customization work to the originally estimated costs for each option.

Demo Fit

• Demo Fit – A pre-prepared, ideal workflow masks missing permissions, exceptions, or integration limitations in everyday use.

• Hidden In-House Work – Configuration, data cleansing, and process customization are not included in the offer but tie up internal resources continuously.

• Unlimited Build – An in-house solution is compared with all conceivable product features instead of the necessary skills.

Scenarios Instead of Checkboxes

• Shared Cost Horizon Implementation, internal work, operation, changes, and decommissioning are calculated over the same timeframe.

Which questions remain after making an objective decision about "Build vs. Buy"?

Connect existing tools or build a central core? Expands on the "Scenarios instead of checkboxes" checkpoint. The guiding question is: When are connected tools sufficient, and when does the organization need a central core system?

A complementary perspective is offered Calculate maintenance effort as part of the architectural decisionIt answers the question: "How does future maintenance effort become part of an architectural decision?"

If you want to put "Build vs. Buy Decisions Based on Objectives" into practice, you can refer to Robust Website Systems . This document focuses on "Sourcing, Costs, and Exit" and "Scenarios Instead of Checkboxes."

Conclusion: Build vs. Buy Decisions Based on Objectives

Vendor marketing loses its influence as soon as every option has to prove itself in the same difficult scenarios. The best choice is not feature-rich, but demonstrably suitable for the specific product lifecycle.

Sources and Further Information

The classification of "Build vs. Buy Decisions Based on Objectives" is based on the following official documentation and standards.

• 11. Choose the right tools and technology – GOV.UK Service ManualOfficial service standard on cost-effective technology selection, total cost of ownership, and the ability to change direction later.

• Choosing Technology: An Introduction – GOV.UK Service ManualOfficial guideline on build vs. buy, total cost, data control, vendor lock-in, prototyping, and modifiability.