Build or buy an AI solution: how to decide

Buying AI software, building a custom solution and combining the two are all valid options. The right decision depends on how distinctive the need is, integration with existing tools, data, operational ownership and the cost of leaving. A persuasive demonstration or initial quotation is not enough to compare them.

1. Define the invariant need

First write the expected outcome without naming a product or technology. This description lets you assess every option against the same scope.

Consider this fictional requirement: “Help account managers prepare a sourced summary from records they are allowed to read, without sending or changing data.” A requirement such as “deploy product X” closes the comparison before the need has been defined.

Specify volume, users, sources, actions, exceptions and service expectations. Identify which parts are standard and which genuinely belong to the organisation’s distinctive way of working.

2. Compare three paths

Option	Relevant when	Point to examine
Existing software	The need is common and the product covers the journey with little adaptation	Functional gaps, data, contract and reversibility
Custom development	The journey is distinctive or needs specific integration and controls	Development, maintenance and operational ownership
Hybrid approach	A standard foundation covers infrastructure while the experience or orchestration remains specific	Responsibility boundary between components

A custom solution nearly always uses existing services and libraries. “Build” does not mean recreating every component. Conversely, “buy” often involves configuring, integrating and governing the product.

3. Test fit before comparing feature lists

Prepare five to ten representative scenarios, including exceptions and denied access. Run them through each option using authorised test data. Check outcome quality as well as how users correct, approve and regain control.

Criterion	Question to verify
Journey	Does the product fit the real tool and moment of work?
Data	Which data enters, where does it travel and how is it deleted?
Access	Are existing permissions enforced through to sources and actions?
Integration	Do the required interfaces exist and have contractual support?
Evaluation	Can you test, explain a failure and track changes?
Operation	Who handles an incident, and within what timeframe?

An isolated prototype can hide identity, permission and recovery problems that appear in the complete journey.

4. Calculate total cost and the cost of change

For purchased software, include licences, usage, integration, configuration, training, support and supplier-driven changes. For custom development, include discovery, development, hosting, external services, monitoring and maintenance.

In both cases, assess the cost of changing volume, model, data source or supplier. Ask how you can retrieve data, configurations, evaluations and useful logs. A low starting cost may come with a high exit cost.

Use the guide to calculating AI project ROI to compare scenarios using the same unit of value. For development and operating cost categories, also consult the AI agent budget guide.

5. Verify actual ownership

Write down who owns data, access, updates, incidents, corrections and launch decisions. A supplier contract does not automatically transfer business responsibility for the use of the system.

Ask which changes may happen without your intervention: model, features, terms of use or interface behaviour. Create a review process for changes that could affect outcomes.

If a partner is involved in the comparison or development, use the questions in choosing an AI development partner to review evidence, handover and operation.

6. Make a reversible decision

For each criterion, record the evidence obtained, remaining unknowns and decision owner. You can limit the initial commitment by scope, duration or integration. Define exit conditions from the outset and how work continues without the solution.

The decision can also be “not yet”. If the process changes weekly or permissions are undefined, stabilising those foundations creates more value than a rushed selection.

Frequently asked questions

Is custom development always more expensive?

Not necessarily over the full lifecycle, but it requires explicit investment and ownership. The comparison depends on scope, volume, adaptations and expected duration of use.

Is a free trial enough to choose?

It can eliminate some options, but it should use representative scenarios in an authorised environment. It does not replace verification of integration, contract, security and operation.

When is a hybrid approach appropriate?

When a standard component adequately covers a non-differentiating part, while the organisation’s own journey, rules or integration require a dedicated layer.