Is Hiring for the Perfect Tech Stack Costing You Great Engineers?

When I speak with technology leaders across Northern Ireland, one hiring challenge comes up repeatedly: they need experienced engineers, but the available candidates do not always match every part of their technology stack.

The instinctive response is often to keep searching for the perfect match. That can feel like the safest option, particularly when a new hire needs to contribute to a live codebase or an important transformation programme. Yet it can also make a difficult search unnecessarily narrow.

My view is that employers should not choose between tech stack knowledge and engineering ability. Both matter. The better approach is to decide which stack knowledge is genuinely essential from day one, which experience can transfer from adjacent technologies, and which skills a strong engineer can realistically learn.

How should employers separate essential, transferable and trainable skills?

Before taking a technology role to market, divide the requirements into three groups: essential from day one, transferable from adjacent technologies and trainable after joining.

• Essential from day one: knowledge the successful candidate must already have to deliver safely and effectively.
• Transferable from adjacent technologies: experience built in comparable languages, frameworks or platforms that rely on the same underlying engineering principles.
• Trainable after joining: tools, processes or domain knowledge a capable engineer can acquire within a realistic timeframe and with the right support.

This is the central test I encourage employers to apply to every technology brief. Each requirement should have a clear reason for sitting in its category.

What technology skills are genuinely essential from day one?

Day-one essentials are the skills a new hire cannot reasonably learn after joining without creating unacceptable delivery, operational or regulatory risk.

They may include:

• deep experience in the core language or framework needed for an immediate delivery deadline;
• ownership of production systems at a similar scale or level of complexity;
• specialist cybersecurity, regulatory or safety-critical expertise;
• direct knowledge of a cloud or infrastructure platform the person must manage immediately; or
• leadership experience relevant to an urgent transformation, migration or recovery programme.

I encourage hiring managers to keep this list short. For every essential requirement, ask: “What would happen if the successful candidate did not have this on their first day?” If the answer is simply that they would need some onboarding, it may not be a true day-one requirement.

What counts as transferable technology experience?

Transferable experience comes from adjacent technologies that rely on similar concepts, patterns and engineering decisions. It is not identical experience, but it can provide a credible route to productivity.

Examples can include:

• Azure experience for an AWS environment when the candidate understands cloud architecture well;
• Angular or Vue experience for a React role when front-end fundamentals are strong;
• Java experience for a C# environment, or the reverse, when object-oriented backend expertise is more important than syntax;
• experience with one relational database where the role uses another; or
• CI/CD and infrastructure-as-code experience gained with comparable tools.

Transferability is role-specific. A general application engineer may move between similar frameworks quickly. A platform specialist responsible for advanced optimisation or a critical migration may need much deeper knowledge of the exact technology. Good recruitment advice should help an employer identify where that line sits.

Which technology skills can be trained after hiring?

Skills are trainable when a capable engineer can acquire them within an acceptable timeframe through documentation, pairing, structured learning and practical use.

These may include:

• an organisation’s preferred testing, monitoring or observability tool;
• a newer framework used in one part of the product;
• internal development and deployment processes;
• sector terminology and company-specific business logic; or
• a useful technology that is not central to the role’s first three to six months.

Calling a skill trainable should not mean leaving the new hire to work it out alone. Employers need to decide who will support them, how much learning time is available and what good progress looks like after 30, 60 and 90 days.

What should employers look for when hiring software engineers?

Employers should look for the right combination of relevant stack knowledge, engineering fundamentals, evidence of learning and sound technical judgement. A candidate’s CV may show React, .NET, Java, AWS or Azure, but it will not show how well they diagnose failures, assess risk or make trade-offs.

Stack knowledge remains important where the role involves an urgent deadline, a complex legacy platform or a highly regulated environment. The risk comes from treating every element of the stack as equally essential without examining the work the person will actually do.

Hiring for capability, not just compatibility

Requiring an exact match across languages, frameworks, cloud platforms and tooling can exclude engineers with strong transferable experience. Their understanding of APIs, data modelling, testing, security, performance and distributed systems moves with them, even when a specific tool does not.

For start-ups, SMEs and new FDI organisations building teams in Belfast, an overly specific brief can delay a key appointment or rule out someone capable of growing with the business.

Does AI make specific programming languages and frameworks less important?

AI can make individual technologies faster to learn and easier to navigate, but it does not make stack knowledge irrelevant. The importance of a specific language or framework depends on the role, the codebase and the risk attached to the work.

Engineers can use AI tools to explain unfamiliar syntax, compare frameworks, explore code, create examples and accelerate routine tasks. That can reduce some of the friction involved in moving between adjacent technologies.

AI may shorten the learning curve, but it does not replace the judgement required to assess whether code is secure, maintainable and suitable for production. An experienced engineer still needs to recognise unreliable suggestions, understand the wider system and take responsibility for the result.

How can employers test transferable engineering skills at interview?

Use realistic scenarios, structured questions and evidence from past work instead of relying mainly on technology trivia. The interview should reflect the capabilities identified in the hiring brief.

1. Ask how the candidate learned an unfamiliar technology

Request a specific example. What knowledge transferred? What did they need to learn? How did they approach the gap, and how long did it take them to become productive? A strong answer should show a repeatable learning process, not simply confidence.

2. Assess engineering fundamentals

Explore testing, debugging, maintainability, security, performance and system design at the level appropriate to the role. Focus on how the person reasons, not whether they can recall a framework feature without context.

3. Look for outcomes, not just tool usage

Ask what changed because of the candidate’s work. Did they improve reliability, reduce incidents, simplify a system, shorten deployment time or help a team deliver a product? Using a technology is not the same as creating value with it.

4. Test judgement with a realistic scenario

Give the candidate an incomplete problem similar to one they would face in the role. Good engineers should identify assumptions, ask useful questions and explain the trade-offs behind their proposed approach.

5. Discuss responsible AI use

If AI-assisted development is part of your environment, ask candidates how they validate generated code, protect confidential information and decide when an AI tool is not appropriate.

What should Northern Ireland employers consider when building tech teams?

Northern Ireland employers should align each technical requirement with the role’s immediate outcomes, the available local talent pool and the organisation’s ability to support learning - benchmarking expectations against realistic local remuneration using our Northern Ireland Tech Salary Guide.

For an established business, the priority may be adding specialist knowledge to an existing team. A start-up may need adaptable engineers who can work across a changing environment. A new FDI organisation launching in Belfast may need senior leaders with experience building teams, establishing culture and translating a global technology strategy into the local market.

Those briefs should not look the same.

The same principle is relevant to employers across the Republic of Ireland. Although every local market has its own dynamics, narrowly defined stack requirements can restrict access to capable engineers on both sides of the border.

What questions should a hiring manager ask before approving a tech job description?

A hiring manager should be able to answer the following questions before the role goes live:

1. What must this person deliver in their first 30, 60 and 90 days?
2. Which technologies must they use independently from day one?
3. Which requirements represent essential engineering concepts rather than a specific tool?
4. What adjacent technologies would provide credible transferable experience?
5. Which skills could be learned within three to six months?
6. What onboarding, mentoring or training will support that learning?
7. Does the interview test the work the person will do, or simply reward familiarity with our terminology?

If these questions are difficult to answer, the brief may not yet be ready for the market.

Find the skills your team really needs

If a highly specific technology brief is limiting your shortlist, MCS Group can help you separate the skills that are essential from those that are transferable or trainable, and introduce engineers with the capability to succeed in the role. Speak to our team or submit a vacancy.