How IT outstaffing companies vet developers (and what to ask)

87% of global senior executives report that their companies aren't prepared to address the tech skill gap. This pressure has been driving the demand for IT outstaffing services as the easiest way to bring in the needed talent.

High demand, in turn, translates into high supply, with a flood of vendors claiming to provide you with top-notch specialists. Yet, in some cases, those promises have little to do with reality, as a quality vetting process that actually ensures the delivery of capable developers is absent.

This guide helps you identify unreliable vendors by explaining how IT outstaffing companies vet developers ideally and what questions to ask to be confident in a vendor's ability to provide truly pre-vetted candidates.

Why vetting quality varies so much between outstaffing vendors

Going through vendors' websites or talking to their representatives, you'll see that all of them market themselves almost identically. 'Top 5% of talent,' 'rigorous screening,' and 'elite developer network' are phrases you'll stumble on everywhere — the marketing language is uniform. The problem is that the approach to pre-vetting is far from being standard, and behind those vendors' phrases, the actual processes vary tremendously.

For one company, multi-stage screening may include architecture interviews with senior engineers, live coding sessions, communication assessments, reference checks, and practical engineering tasks. For another, it may involve just a 20-minute recruiter call, a basic online coding test, and a quick GitHub profile review.

Many clients discover and actually feel the difference only after onboarding, when it becomes clear that the provided developer isn't as senior as expected.

Your vendor's poor vetting process can cost you a lot. Many sources estimate that a bad hire may cost at least 30% of the employee's first-year earnings, once you add up salary, onboarding, management time, rework, delivery delays, and the extra workload that usually falls on the rest of the team.

However, this doesn't mean all outstaffing vendors are unreliable. There are also those who invest in engineering-led screening because they understand that weak placements affect retention, delivery quality, and reputation.

The challenge is that strong and weak vendors often sound almost exactly the same. The real difference only becomes visible once you look closely at how outstaffing companies screen developers.

What a rigorous outstaffing vetting process actually looks like

Developer vetting is aimed at assessing a candidate against technical experience, real-world engineering judgment, communication, collaboration, reliability, and role fit. One 30-min interview cannot help you reveal all of these. This is why proper developer evaluation is always layered, with each stage covering a certain type of risk, from exaggerated seniority in a CV to weak communication skills.

Ideally, a staff augmentation vetting process includes the following:

Stage 1 — Initial screening and profile review

At this stage, managers determine whether the candidate's background and expertise claimed in the CV match the role requirements.

A strong vendor usually carefully reviews:

• project complexity

• responsibilities

• career progression

• product scale

• signs of real ownership.

For example, there is a difference between a developer who implemented isolated frontend tasks in a large enterprise team and one who independently designed modules, improved architecture, handled incidents, and participated in technical decision-making, even if both list the same stack and years of experience.

Simultaneously, hiring managers look for inconsistencies like:

• overlapping timelines

• unclear project descriptions

• unrealistic technology combinations

• sudden jumps in seniority.

Good vendors often go further and review GitHub activity, portfolio quality, open-source contributions, or technical publications, if available, to see the big picture, not just standard job descriptions.

Weak vendors, meanwhile, usually focus on keyword matching only. They move profiles forward once they see the needed stack without checking how much hands-on experience candidates really have with those technologies.

Stage 2 — Technical interview

Here, the goal is to evaluate the developer's technical expertise as well as their mindset and approach to solving unfamiliar problems.

To understand how candidates reason, break down tasks, and justify tech decisions, interviewers don't ask trivial questions but build a discussion around system design, scalability, trade-offs, challenges, observability, tech debt, incident handling, etc. Also, they ask a lot of follow-up questions rather than jumping from topic to topic. This helps reveal the depth of knowledge.

Considering all these, tech interviews can be efficient only when conducted by senior engineers, architects, or tech leads.

Weak vendors, in turn, sometimes delegate such interviews to recruiters or non-technical coordinators who use a predefined question list. As a result, the process often turns into a formal quiz rather than a proper developer evaluation.

Stage 3 — Live coding session

A live coding session is an important element of developer vetting in outstaffing. When executed properly, it shows how a developer solves real-world problems in real time.

That's why strong vendors use practical engineering tasks instead of purely theoretical exercises. Depending on the role, candidates may be asked to:

• debug broken functionality

• improve an existing codebase

• review another engineer's code

• write tests

• optimize performance

• or implement a feature with realistic business constraints.

The results should be reviewed by experienced engineers rather than being scored automatically. Ideally, the coding task is followed by a discussion where the candidate explains their solution and the interviewer asks clarifying questions, challenging the approach where needed.

One more nuance is that tasks should always be calibrated to seniority. If every candidate receives the same generic coding challenge regardless of level, that's usually the sign of a shallow approach.

In fact, weak vendors often use:

• multiple-choice quizzes

• timed algorithm tasks

• or automated coding platforms.

These assessments may reveal whether someone can solve certain problems under time pressure, but they show almost nothing about how a developer works in a production environment.

Stage 4 — Behavioral and communication assessment

This is something that many outstaffing companies and employers underestimate.

A developer may write clean code but still create delivery problems because of behaviour issues. For example, they may:

• fail to raise blockers early

• misunderstand requirements

• lack responsiveness

• or struggle to collaborate with non-tech stakeholders.

In fact, communication and behavior problems drive 89% of hiring failures, while technical skills account for only 11% of hiring failures.

Strong vendors understand this and treat communication assessment as a separate stage rather than an afterthought.

As a rule, candidates are evaluated on:

• spoken and written English

• clarity of explanation

• responsiveness

• async communication habits

• ownership mindset

• and the ability to discuss technical topics with both technical and non-technical stakeholders.

Candidates may be asked to explain a complex concept in simple terms or describe how they handle situations when their approach conflicts with that of other engineers on the team.

As for weak vendors, they often skip this stage entirely or reduce it to a 10-minute culture fit chat and a quick conclusion that the candidate speaks understandable English.

Stage 5 — Reference check and background verification

Even with well-structured interviews, you cannot evaluate the abilities of candidates to the full extent. Reference checking is an additional layer that helps verify a developer's reliability, professionalism, ownership, consistency, and actual involvement in previous projects.

While reviewing references provided by a candidate, good vendors also do independent research and contact former managers, asking about:

• employment history

• projects

• role responsibilities

• ability to work independently

• collaboration quality, etc.

References are especially important for senior-level roles where technical leadership, decision-making, and communication skills matter just as much as coding ability.

Weak vendors usually skip this stage or rely entirely on references shared by candidates. That creates risk, especially when hiring developers into critical product or architecture-heavy roles.

So, the approach to developer screening can differ a lot from vendor to vendor, and you should keep this in mind when considering a new partnership. The table below helps highlight the difference between strong and weak staff augmentation vetting processes.

How vetting should differ for senior vs. junior developers

A proper vetting process isn't just multi-layered but is also calibrated to the seniority level of the candidate being assessed.

Different seniority levels come with different expectations and, therefore, require different evaluation approaches.

For example, junior developers aren't assumed to have deep architectural thinking or extensive production experience. They may still need oversight, and this is totally ok.

So, evaluating juniors, it's important to understand:

• how well they know coding fundamentals

• how quickly they learn

• how fast they adapt

• how clearly they communicate.

Senior-level evaluation is a completely different story. A senior developer isn't just someone who writes code faster and knows more frameworks. They're responsible for making decisions that affect system scalability, maintainability, reliability, speed, and the work of the whole engineering team.

That's why the evaluation process for senior developers should cover checks for:

• system design

• technical leadership

• architecture discussions

• trade-off awareness

• production incident handling

• and decision-making under ambiguity

Discussions centered around scaling challenges, maintainability vs. speed, and architecture can tell you a lot about a seniority level.

If a vendor uses almost identical screening approaches for every candidate, regardless of level, they simply run a filter instead of conducting a real evaluation. Such a vetting process is unlikely to deliver good specialists.

And if a weak junior developer may just require additional supervision, a weak senior developer can cause long-term problems, increase technical debt, slow down delivery, and affect the performance of the whole team.

That's why never neglect to ask potential outstaffing partners about how their technical assessment differs for senior versus mid-level candidates.

Key questions to ask outstaffing vendors before committing

Most vendors have attractive websites and sound pretty convincing, presenting their services. However, real professionalism shows up when you ask them very specific, slightly uncomfortable questions, like the following ones:

Questions about their vetting process

1. What does your developer assessment process look like?

A vendor with a refined process will be glad to spill the details. If you hear something vague, like 'we have a multi-stage rigorous process' without any specifics, that's no good.

2. Who leads your technical interviews?

In credible staff augmentation companies, technical interviews are always run by senior engineers or tech leads. If it's recruiters or non-technical people doing the interviews, the results of the technical assessment aren't reliable.

3. What is your acceptance rate?

Competent vendors have selective pipelines and track their acceptance rate. Therefore, they can give you a fair number, often around 10-15%. If the answer is general — for example, 'We hire only the best' without details — it's worth being cautious.

4. How do you conduct coding assessments, and who reviews the results?

A proper assessment suggests real-world tasks, production-like scenarios, seniority calibration, and review by senior engineers. If your vendor focuses only on algorithmic tests and doesn't engage engineers in the evaluation process, don't expect really pre-vetted developers from them.

Questions about senior-level evaluation

5. How do you verify the architectural thinking of senior developers?

Using HackerRank or standard coding tests isn't enough to understand how senior engineers think in real-world situations. Opt for a vendor who incorporates system design discussions, real problem-based scenarios, and follow-up questions that show how candidates make trade-offs and tech decisions.

6. How do you approach employment history and project claim verification?

It's a good sign when a vendor doesn't just take CVs at face value but verifies details by asking developers to explain specific projects, clarify their role, and elaborate on their personal contributions.

Questions about replacements

7. What is your replacement policy?

If a developer doesn't meet expectations in the first two months, reliable vendors provide a no-cost replacement. If the replacement terms sound vague, or worse, aren't clearly defined in the agreement, you'd better think twice before moving forward.

8. What percentage of placements result in replacement requests, and what are the most common reasons?

The answer to this question can tell a lot about vetting quality. If the vendor has low replacement rates and can clearly explain the reasons behind those few replacements that happened, that's usually a good sign. Vague answers or inconsistent numbers often point to weak screening.

Questions about transparency and process accountability

9. Can I speak with your 2-3 current clients about their experience with the developers you placed?

Trustworthy vendors are always ready to share with you the contact information of their clients so that you can get some feedback directly from them. This level of transparency is what you should look for.

10. Will I be able to run my own technical interview with the candidate before agreeing to hire them?

For the outstaffing model, this is standard. Clients often run their own technical interviews or live sessions. If a vendor discourages this, it's a warning sign about their confidence in their own vetting.

If you aren't sure how to evaluate an outstaffing company, ask the questions above. If a vendor can't give clear and specific answers, that alone tells you whether it makes sense to move forward with them.

Red flags in vendors' answers about their vetting process

We've touched on weak answers above, but it's also worth highlighting specific red flags you may notice when vendors describe their vetting process. This way, you'll know where to pause and ask for more details.

• Claiming to have a proprietary screening system without explaining how it actually works — 'proprietary' doesn't always equal good. In many cases, it's just a catchy word behind which vendors hide their unwillingness to stay transparent.

• Stating that their developers are pre-vetted by their platform — this often indicates reliance on automated tests only, with no human reviews in place.

• Promising to provide candidates within 24-48 hours — that speed is usually only possible if the vendor has pre-vetted candidates on the bench who are ready to go. If that's not the case, it often suggests they're sourcing and filtering candidates too quickly, without proper evaluation.

• Guaranteeing 100% candidate suitability — if a vendor says this without clearly defining what 'suitability' means, how it's measured, or what happens if expectations aren't met, it's usually just a marketing promise.

• Inability to clearly explain who conducts technical interviews or what their background is — this often signals that experienced engineers aren't really engaged in the interviewing process.

• No clear data on acceptance rate or vetting pass rate — without funnel visibility, it's difficult to understand how selective the process is.

• Reluctance to share assessment results or arrange a client-side technical interview — lack of transparency and hesitation can be a warning sign that the evaluation process isn't thorough enough.

If, while talking to your potential outstaffing partner, you spot several of these red flags, you'd better go away, as their vetting process is more marketing than engineering.

What you should run yourself, even with a pre-vetted developer

Whether you work with a new or existing outstaffing partner, it is important to arrange a short internal technical interview with pre-vetted developers. Get it right: It's not about having no trust in your vendor or outstaffing developer vetting process but about ensuring full alignment before starting engagement. That's the norm, and trustworthy vendors are usually open to setting up such meetings online or offline.

Your goal here isn't to repeat the whole technical assessment from scratch. By this time, that part should already be covered. Your focus should be on:

• communication style

• problem-solving skills

• natural fit with your team dynamics

In these terms, we'd recommend you pay attention to

• How developers explain their recent projects, responsibilities, and contributions — the level of detail, particularly when they describe ownership and delivered value, is important here.

• How they behave when they don't know the answer — competent developers are usually honest about having no ready answer and try to reason through it instead of guessing.

• How they engage with your product context — look for candidates who ask relevant questions, pick up on constraints, and try to understand what you build and how.

Apart from an internal interview, it's also worth adding one more verification layer — a short paid trial period. A 1-2 week engagement on a real task shows you more than interviews alone can: actual developers' performance with your processes, tools, standards, and limitations.

How Devico vets developers before they reach you

Having been in the business for over a decade, Devico knows that an efficient IT outstaffing screening process is the key thing that makes the model work. Therefore, our vetting process is a sequence of thorough checks that assess experience, real technical ability, and communication in context.

In fact, we use nearly the same framework described above:

Step 1: Screening applications by carefully reviewing work history, tech stack, and personal contributions to projects.

Step 2: Checking the capabilities of every candidate through real-world engineering tasks, not theoretical tests.

Step 3: Running pair programming and debugging sessions to see how candidates solve problems and perform under pressure.

Step 4: Assessing mid-to-senior developers on their ability to design scalable architecture and make trade-off decisions.

Step 5: Holding a structured interview to evaluate communication skills, ownership mindset, and remote-work habits.

Step 6: Setting up a final interview with one of our senior tech leads before making the final decision.

With all of that in place, by the time we present you a candidate, they've already been screened by our engineers across different criteria.

Nevertheless, this shouldn't substitute your own validation, which is why we encourage our clients to run internal interviews with candidates. And we're happy to answer any of the vendor questions from this article, or any others you might have, so you can understand whether we're the right fit.

Conclusion

A thorough vetting process is what differentiates a reliable outstaffing partner from a superficial one. Often, there is a large gap between a vendor's marketing language and their actual screening process. Understanding how IT outstaffing companies vet developers and knowing which questions to ask to surface the truth is the best way to protect yourself before making a commitment.

The most efficient approach is pretty simple: ask all potential partners the same questions and compare the specificity of their answers. A vendor with a rigorous process will welcome the detailed review. One with a surface-level process will avoid it.

At Devico, we're always ready to tell you how we evaluate developers as well as to answer all your related questions. So, if you'd like to discuss anything in more detail, feel free to reach out.