How to Hire AI Developers for Custom AI Product Development

Published on
April 29, 2026
Updated on
April 29, 2026
How to Hire AI Developers for Custom AI Product Development
NineTwoThree's guide to hiring AI developers: roles, skills, interview techniques, job description templates, and what to look for in a development partner.

Every week, we talk to companies that tried to build a custom AI product, ran into trouble, and came to us for a second attempt. In most cases, the project failed for one of two reasons: either the wrong people were hired, or the right people were hired for the wrong roles. Sometimes both.

Hiring AI developers well is not a simple task. It requires clarity about what you're building, who you need to build it, and how to verify that the candidates in front of you actually know what they're doing. This guide covers all three.

AI Is Not One Discipline

Before you write a single job posting, understand that "AI developer" is an umbrella term covering at least nine distinct roles, each with a different function and a different skill set. Treating them as interchangeable is one of the most expensive mistakes a product team can make.

Here is the actual breakdown:

  • AI Product Owner / Product Manager. Bridges business objectives with technical execution. Defines the product strategy, sets success metrics, and ensures the AI solution is solving a real problem, not just a technically interesting one.
  • AI Developer. Implements models and integrates them into applications. Responsible for prompt engineering, fine-tuning, and scalability. This is often the role people mean when they say hire AI developers, but it's far from the only one you need.
  • AI Architect. Designs the high-level system architecture. Selects technologies and ensures the infrastructure can support the workload now and at scale.
  • Machine Learning Engineer. Takes trained models and operationalizes them into production systems. Handles latency, cost control, monitoring, and retraining pipelines. This is a different job from building the model.
  • Data Scientist. Explores and validates data to make sure model inputs are reliable and unbiased. If your data scientist is weak, your model will be wrong in ways that are very hard to debug.
  • NLP Engineer. Specializes in language models and fine-tuning them for tasks like speech recognition, text analysis, and conversational AI. Critical for any product involving language.
  • Computer Vision Engineer. Develops algorithms for visual data interpretation. Required for products involving image recognition, video analysis, or object detection.
  • AI Infrastructure Engineer. Maintains the cloud and on-premise infrastructure that supports AI workloads at scale. Often overlooked until a system falls over.
  • AI Product Designer. Focuses on user experience and ensures AI features feel intuitive rather than confusing or intrusive.
Role Core Responsibility Key Skills Typical Stack When to Hire
AI Product Owner / PM Define product strategy, bridge business and technical teams Agile, AI literacy, communication Jira, Trello, Miro Any stage
AI Developer Implement and integrate models into applications Python, prompt engineering, fine-tuning TensorFlow, PyTorch, LangChain Early and mid-stage
AI Architect Design system architecture, select technologies System design, cloud platforms, security AWS, Azure, Kubernetes, Terraform Before build begins
Machine Learning Engineer Operationalize models into production ML algorithms, CI/CD, monitoring TensorFlow, Docker, MLflow Scaling stage
Data Scientist Data analysis, feature engineering, model prototyping Statistics, Python, R, SQL Python, R, Tableau Early and ongoing
NLP Engineer Build and fine-tune language models NLP techniques, transformer models Hugging Face, spaCy, NLTK Language-based products
Computer Vision Engineer Build visual data algorithms Deep learning, image processing OpenCV, TensorFlow, YOLO Vision-based products
AI Research Scientist Develop novel models and algorithms Advanced ML theory, research methodology PyTorch, JAX, MATLAB R&D-heavy projects
AI Infrastructure Engineer Build and maintain AI infrastructure Cloud infrastructure, vector databases AWS, Azure, Pinecone, Kubernetes Scaling and enterprise
AI Product Designer UX design, integrate AI into user flows UX research, prototyping Figma, Miro Any user-facing product

Which of these you need depends entirely on where your project is. Early-stage products often need an AI Developer and a Data Scientist to move fast. Scaling products requires Machine Learning Engineers, MLOps Engineers, and Data Engineers. Enterprises in regulated sectors add AI Infrastructure Engineers and AI Product Managers for compliance and alignment. Getting this wrong from the start means paying twice.

What Skills to Actually Look For

When you hire generative AI developers or any AI specialist, there are three categories of skills that matter.

Technical foundation

Proficiency in Python is non-negotiable for most AI roles. Beyond that, candidates should have hands-on experience with machine learning frameworks like TensorFlow, PyTorch, or Scikit-learn, and familiarity with deep learning architectures such as CNNs, RNNs, and Transformers. Strong command of data structures, algorithms, and big data tooling rounds this out.

Domain knowledge

An AI developer who has worked in healthcare, finance, or logistics will produce better results for a company in those industries than a generalist who hasn't. Domain experience means fewer surprises when real data arrives and faster iteration on what actually matters.

Soft skills and adaptability

Communication, critical thinking, and the ability to articulate model limitations to non-technical stakeholders are not optional. AI teams that cannot explain what they've built, or why it failed, are expensive. Given how fast the field moves, continuous learning is also something to screen for seriously. Candidates who are not actively keeping up with new developments are already behind.

AI didn't flatten the skill curve. It actually stretched it. AI is not replacing engineers, it's actually amplifying their baseline. Good devs now deliver way more than they were before because you can really support yourself using these models. But on the other side, weak devs now create 10 times more spaghetti code, because speed without judgment is a liability.
Vitalijus Cernej
Vitalijus Cernej
Lead ML Engineer
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How to Write a Strong AI Developer Job Description

A weak AI developer job description produces a long list of unqualified applicants. A strong one filters the right people in and the wrong people out.

Start with the business outcome you're hiring for, not the technology. "We're building a document intelligence tool that reduces manual review time for our legal team by 60%" is more useful to a skilled candidate than "we are looking for an AI developer to work on LLMs." The former tells them what success looks like. The latter tells them nothing.

From there, be specific about the technical stack and what you actually expect them to do. If you need someone who can fine-tune a model and integrate it into an existing product via API, say that. If you need someone who can own the entire ML pipeline from data ingestion to monitoring, say that too. Ambiguity at the job description stage becomes confusion and misaligned expectations during the project.

Include a clear line about the stage of your product. Is this greenfield? A second attempt after a failed build? An existing system that needs to be extended? Experienced AI engineers will make different decisions about whether to apply based on this context.

Job description template

[Job Title] — [Team or Product Name]

What we're buildingOne to two sentences on the product and the problem it solves. Include the business outcome you're working toward, not just the technology stack.

What this role is responsible forThree to five specific deliverables or ownership areas. Avoid generic phrases like "contribute to AI initiatives." Name the actual work: fine-tuning a domain-specific model, owning the evaluation pipeline, building the data ingestion layer.

Technical requirementsList the skills and tools that are genuinely required, and separate them from nice-to-haves. If Python and PyTorch are required but experience with a specific vector database is optional, say so. Candidates read these lists carefully.

Where the product is todayPrototype, early production, scaling, or legacy system that needs extension. This context matters to experienced candidates.

Team and working setupWho they will work with, how decisions get made, and how the team operates. Remote or on-site, synchronous or async, embedded with product or separate.

How you will evaluate candidatesA brief description of the interview process. Candidates who have options will prioritize roles where they know what to expect.

How to Run the Interview Process

The biggest interview mistake companies make is testing general coding ability and then hoping the candidate can also handle AI-specific challenges. Those are not the same thing.

A solid interview process assesses a candidate across technical ability, domain judgment, problem-solving under ambiguity, how they use AI tools, communication skills, and performance under real conditions.

Technical assessment

A hands-on coding challenge that tests the specific skills in the job description, not generic algorithm puzzles. Debugging a broken training pipeline is closer to what these developers actually do than reversing a binary tree.

For example:

  • Give a candidate a RAG pipeline with a retrieval bug and ask them to identify and fix it
  • Ask them to refactor a prompt that is producing inconsistent outputs
  • Hand them a dataset with obvious quality issues and ask what they would do before passing it to a model

You are looking for how they think through the problem, not just whether they land on the right answer.

Scenario-based questions

Give candidates real problems from your domain. You're testing judgment, not just knowledge.

For example:

  • "Our model performs well in testing but degrades after two weeks in production. Walk me through how you'd diagnose that."
  • "A stakeholder wants to use the model's output to make a financial decision. What would you need to validate before you'd be comfortable with that?"
  • "We have class imbalance in our training data. How would you approach that, and what are the tradeoffs of each method?"

Candidates who give structured, nuanced answers to questions like these have usually shipped something real.

Problem-solving exercises

A take-home project is worth more than any technical interview question. It shows how a candidate approaches ambiguity, how they communicate their reasoning, and whether they can deliver something usable rather than just something that runs.

Keep the scope tight — three to four hours, not a week. The goal is not to get free work out of candidates. It's to see how they operate when no one is watching and the requirements aren't spelled out.

Example briefs:

  • "Here is a CSV of customer support tickets from a SaaS product. Build a simple classifier that routes tickets to the right team. Document every assumption you made about the data and explain why you chose the approach you did."
  • "Here is a set of 200 product descriptions in varying quality. Build a pipeline that normalizes and enriches them using an LLM. Include a note on how you would evaluate whether the outputs are good enough to ship."
  • "Here is a broken RAG implementation that retrieves irrelevant chunks most of the time. Diagnose the problem, fix it, and explain what you changed and why."

What you are evaluating is the quality of their decisions, not just the output. A candidate who delivers a clean solution with no explanation of their reasoning is less valuable than one who delivers something imperfect and can clearly articulate where they would take it next.

AI collaboration assessment

If you're hiring generative AI developers, evaluate how they use AI tools as part of their process. A candidate who has never integrated an API, built a RAG pipeline, or thought carefully about prompt behavior in edge cases is not a generative AI developer regardless of what the resume says. Also watch for over-reliance on AI assistance as a substitute for actual understanding. That pattern tends to collapse under production conditions.

For example, ask:

  • "Walk me through a prompt you've engineered for a real task. What decisions did you make and why?"
  • "What happens when the model ignores the prompt? How do you test for that?"
  • "Tell me about a time an LLM produced a confident but wrong answer in your system. How did you catch it?"

Candidates who have concrete answers to these questions have actually worked with LLMs outside of a demo environment.

The general problem is that new engineers trust the model too much. They take things for granted, and only people with previous experience distrust it in the right places. But for people who haven't coded without LLMs, it's like a cheat code on the exam. Your brain stops working because you just run whatever it generated. This is a huge liability, because yes, coding benchmarks are getting better, but if you ask it to work with something which was launched like a year ago, you're really going to struggle, because LLMs didn't learn to code — they were manually fine-tuned by people to solve some tasks.
Vitalijus Cernej
Vitalijus Cernej
Lead ML Engineer
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Behavioral questions

Technical skill alone does not make a reliable team member. An AI engineer who cannot communicate with stakeholders, adapt when requirements change, or give and receive feedback clearly will slow a project down regardless of how strong their model work is. These questions are not filler — they reveal how a candidate operates under real conditions.

For example, ask:

  • "Tell me about a time a model you built didn't perform as expected in production. What did you do?"
  • "How have you explained a model's limitations to a non-technical stakeholder?"
  • "Describe a project where the requirements changed significantly mid-build. How did you handle it?"
  • "What do you do when you disagree with a product decision that affects the AI system you're building?"

Pay attention to whether they talk about outcomes and lessons, or just describe what happened. Candidates who reflect on what they would do differently are usually the ones who have actually learned from it.

Live task with screen share

Theory-based interviews have a ceiling. Candidates can answer almost any conceptual question with enough preparation — or with a browser tab open in the background. A short live task under screen share cuts through that.

The task does not need to be complex. Something that a competent engineer should be able to work through in 15 minutes using their own knowledge and basic problem-solving is enough. The point is to observe how they think in real time: do they read the error message before reaching for a tool, do they ask clarifying questions, do they know when to stop and reassess?

It's very hard right now to perform interviews because people tend to screen share and you can answer most theoretical questions by just using ChatGPT. But we do have online coding tasks with screen share, and one of the things which is really surprising — no one from us expected it — is that we give tasks which are really trivial if you can just Google and use your brain. This is a 15-minute task, honestly nothing crazy. From all of our interviews, more than 90% fail with it. And from the people who have used LLM support to solve it, not a single person has solved it, because every time you throw this task at an LLM, it just creates another task which they again throw at an LLM to debug, and it's just a rabbit hole.
Vitalijus Cernej
Vitalijus Cernej
Lead ML Engineer
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Scope the Project Before You Hire

One of the most common ways AI hiring goes wrong is that the project scope is undefined when the engineers start. You bring someone in, they build something, and then three months later you realize what was built does not match what was needed because nobody agreed on what "done" looked like.

Before you hire gen AI developers for a custom product, nail down the following:

  • What problem does this solve, and how will you measure that it's solved?
  • What data do you have, and what is its current quality?
  • What are the security and compliance requirements?
  • Who owns what parts of the project?
  • What does the delivery timeline look like, with actual milestones?
  • What is the budget, and how is it structured?
  • What are the acceptance criteria for each deliverable?
  • How will scope changes be handled?

This is not bureaucracy. This is the difference between a project that ships and a project that stalls at 80% for six months while everyone argues about what was agreed.

A written scope document that covers these elements forces alignment before the first line of code is written. It also gives you a basis for evaluating candidates, because people who ask good questions about scope during the interview process are usually people who have seen projects fail without it.

Where to Find the Right People

Job boards will get you volume. They will not reliably get you the right candidates for specialized AI roles.

The most effective sourcing channels for AI talent are GitHub (look at what they've actually built), open-source project communities, specialized Discord and Slack communities organized around specific tools or research areas, academic networks for research-oriented roles, and vetted talent networks that vet for AI-specific skills.

For custom AI product work, agencies that specialize in AI development are often faster and more reliable than a pure hiring play. The project gets a team that has built this before, with established practices around data handling, model evaluation, edge case management, and production deployment.

If you are weighing that option, our guide on how to hire an AI agency covers what to look for and what to avoid. Whether you hire a developer directly or engage a development partner, the questions you ask and the standards you hold should be the same.

Transparency Is Not Optional

When you hire AI developers for production systems, especially in regulated industries, the ability to explain how a model makes decisions is a technical requirement, not a nice-to-have. Hiring engineers who treat model interpretability as someone else's problem is a risk. Bias audits, explainability tooling, and responsible data handling should be part of how your AI team operates, not afterthoughts introduced when a compliance team asks uncomfortable questions.

Screen for this explicitly. Ask candidates how they have approached fairness in a past project. Ask how they would explain a model failure to a business stakeholder. Ask what they do when a model performs well in testing and poorly in production. The answers tell you a lot about how they think.

Verifying a Development Partner

If you are evaluating agencies rather than individuals, the due diligence process is similar. Look for consistent evidence of problem-solving, delivery against real business goals, and honest communication when things got difficult. Client reviews on platforms like Clutch verify that past clients actually exist and actually had the experience described.

Red flags to take seriously: vague claims about AI capabilities with no case studies behind them, pricing that cannot be explained with reference to actual scope, and reluctance to discuss how they have handled project failures. Every team that has shipped real AI products has a failure story. Teams that claim otherwise have not shipped much.

Closing Thoughts

Getting AI development right starts long before the first interview. It starts with defining what you are building, why it matters, and which roles are actually required to build it well. Once that foundation exists, hiring becomes a structured process rather than a series of best guesses.

A few things that are worth holding onto:

Map the roles you need against the actual work, not against titles you have seen elsewhere. Write job descriptions around outcomes, not just technologies. Test for judgment and judgment under real conditions, not just technical knowledge in the abstract. Define scope in writing before anyone writes code.

The companies that build AI products with real ROI are not the ones that hired the most aggressively or moved the fastest. They are the ones that knew what they needed and were deliberate about how they got it.

Hiring One Partner For All AI Roles

We have built over 150 AI products for clients including FanDuel, Consumer Reports, Experian, and SimpliSafe. Our team of PhD-level engineers and certified product managers has been doing this for eight years, and we have been ranked alongside Microsoft, NVIDIA, and IBM as a top 5 AI consultancy.

If you are figuring out how to hire a developer for your AI project, or trying to build the right team structure before committing to a major build, we can help you think it through.

Schedule a free discovery call with our founders. We will not hand you off to a sales team. You will talk directly to the people who have built projects like yours.

Book a discovery call with NineTwoThree

Every week, we talk to companies that tried to build a custom AI product, ran into trouble, and came to us for a second attempt. In most cases, the project failed for one of two reasons: either the wrong people were hired, or the right people were hired for the wrong roles. Sometimes both.

Hiring AI developers well is not a simple task. It requires clarity about what you're building, who you need to build it, and how to verify that the candidates in front of you actually know what they're doing. This guide covers all three.

AI Is Not One Discipline

Before you write a single job posting, understand that "AI developer" is an umbrella term covering at least nine distinct roles, each with a different function and a different skill set. Treating them as interchangeable is one of the most expensive mistakes a product team can make.

Here is the actual breakdown:

  • AI Product Owner / Product Manager. Bridges business objectives with technical execution. Defines the product strategy, sets success metrics, and ensures the AI solution is solving a real problem, not just a technically interesting one.
  • AI Developer. Implements models and integrates them into applications. Responsible for prompt engineering, fine-tuning, and scalability. This is often the role people mean when they say hire AI developers, but it's far from the only one you need.
  • AI Architect. Designs the high-level system architecture. Selects technologies and ensures the infrastructure can support the workload now and at scale.
  • Machine Learning Engineer. Takes trained models and operationalizes them into production systems. Handles latency, cost control, monitoring, and retraining pipelines. This is a different job from building the model.
  • Data Scientist. Explores and validates data to make sure model inputs are reliable and unbiased. If your data scientist is weak, your model will be wrong in ways that are very hard to debug.
  • NLP Engineer. Specializes in language models and fine-tuning them for tasks like speech recognition, text analysis, and conversational AI. Critical for any product involving language.
  • Computer Vision Engineer. Develops algorithms for visual data interpretation. Required for products involving image recognition, video analysis, or object detection.
  • AI Infrastructure Engineer. Maintains the cloud and on-premise infrastructure that supports AI workloads at scale. Often overlooked until a system falls over.
  • AI Product Designer. Focuses on user experience and ensures AI features feel intuitive rather than confusing or intrusive.
Role Core Responsibility Key Skills Typical Stack When to Hire
AI Product Owner / PM Define product strategy, bridge business and technical teams Agile, AI literacy, communication Jira, Trello, Miro Any stage
AI Developer Implement and integrate models into applications Python, prompt engineering, fine-tuning TensorFlow, PyTorch, LangChain Early and mid-stage
AI Architect Design system architecture, select technologies System design, cloud platforms, security AWS, Azure, Kubernetes, Terraform Before build begins
Machine Learning Engineer Operationalize models into production ML algorithms, CI/CD, monitoring TensorFlow, Docker, MLflow Scaling stage
Data Scientist Data analysis, feature engineering, model prototyping Statistics, Python, R, SQL Python, R, Tableau Early and ongoing
NLP Engineer Build and fine-tune language models NLP techniques, transformer models Hugging Face, spaCy, NLTK Language-based products
Computer Vision Engineer Build visual data algorithms Deep learning, image processing OpenCV, TensorFlow, YOLO Vision-based products
AI Research Scientist Develop novel models and algorithms Advanced ML theory, research methodology PyTorch, JAX, MATLAB R&D-heavy projects
AI Infrastructure Engineer Build and maintain AI infrastructure Cloud infrastructure, vector databases AWS, Azure, Pinecone, Kubernetes Scaling and enterprise
AI Product Designer UX design, integrate AI into user flows UX research, prototyping Figma, Miro Any user-facing product

Which of these you need depends entirely on where your project is. Early-stage products often need an AI Developer and a Data Scientist to move fast. Scaling products requires Machine Learning Engineers, MLOps Engineers, and Data Engineers. Enterprises in regulated sectors add AI Infrastructure Engineers and AI Product Managers for compliance and alignment. Getting this wrong from the start means paying twice.

What Skills to Actually Look For

When you hire generative AI developers or any AI specialist, there are three categories of skills that matter.

Technical foundation

Proficiency in Python is non-negotiable for most AI roles. Beyond that, candidates should have hands-on experience with machine learning frameworks like TensorFlow, PyTorch, or Scikit-learn, and familiarity with deep learning architectures such as CNNs, RNNs, and Transformers. Strong command of data structures, algorithms, and big data tooling rounds this out.

Domain knowledge

An AI developer who has worked in healthcare, finance, or logistics will produce better results for a company in those industries than a generalist who hasn't. Domain experience means fewer surprises when real data arrives and faster iteration on what actually matters.

Soft skills and adaptability

Communication, critical thinking, and the ability to articulate model limitations to non-technical stakeholders are not optional. AI teams that cannot explain what they've built, or why it failed, are expensive. Given how fast the field moves, continuous learning is also something to screen for seriously. Candidates who are not actively keeping up with new developments are already behind.

AI didn't flatten the skill curve. It actually stretched it. AI is not replacing engineers, it's actually amplifying their baseline. Good devs now deliver way more than they were before because you can really support yourself using these models. But on the other side, weak devs now create 10 times more spaghetti code, because speed without judgment is a liability.
Vitalijus Cernej
Vitalijus Cernej
Lead ML Engineer
Share
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How to Write a Strong AI Developer Job Description

A weak AI developer job description produces a long list of unqualified applicants. A strong one filters the right people in and the wrong people out.

Start with the business outcome you're hiring for, not the technology. "We're building a document intelligence tool that reduces manual review time for our legal team by 60%" is more useful to a skilled candidate than "we are looking for an AI developer to work on LLMs." The former tells them what success looks like. The latter tells them nothing.

From there, be specific about the technical stack and what you actually expect them to do. If you need someone who can fine-tune a model and integrate it into an existing product via API, say that. If you need someone who can own the entire ML pipeline from data ingestion to monitoring, say that too. Ambiguity at the job description stage becomes confusion and misaligned expectations during the project.

Include a clear line about the stage of your product. Is this greenfield? A second attempt after a failed build? An existing system that needs to be extended? Experienced AI engineers will make different decisions about whether to apply based on this context.

Job description template

[Job Title] — [Team or Product Name]

What we're buildingOne to two sentences on the product and the problem it solves. Include the business outcome you're working toward, not just the technology stack.

What this role is responsible forThree to five specific deliverables or ownership areas. Avoid generic phrases like "contribute to AI initiatives." Name the actual work: fine-tuning a domain-specific model, owning the evaluation pipeline, building the data ingestion layer.

Technical requirementsList the skills and tools that are genuinely required, and separate them from nice-to-haves. If Python and PyTorch are required but experience with a specific vector database is optional, say so. Candidates read these lists carefully.

Where the product is todayPrototype, early production, scaling, or legacy system that needs extension. This context matters to experienced candidates.

Team and working setupWho they will work with, how decisions get made, and how the team operates. Remote or on-site, synchronous or async, embedded with product or separate.

How you will evaluate candidatesA brief description of the interview process. Candidates who have options will prioritize roles where they know what to expect.

How to Run the Interview Process

The biggest interview mistake companies make is testing general coding ability and then hoping the candidate can also handle AI-specific challenges. Those are not the same thing.

A solid interview process assesses a candidate across technical ability, domain judgment, problem-solving under ambiguity, how they use AI tools, communication skills, and performance under real conditions.

Technical assessment

A hands-on coding challenge that tests the specific skills in the job description, not generic algorithm puzzles. Debugging a broken training pipeline is closer to what these developers actually do than reversing a binary tree.

For example:

  • Give a candidate a RAG pipeline with a retrieval bug and ask them to identify and fix it
  • Ask them to refactor a prompt that is producing inconsistent outputs
  • Hand them a dataset with obvious quality issues and ask what they would do before passing it to a model

You are looking for how they think through the problem, not just whether they land on the right answer.

Scenario-based questions

Give candidates real problems from your domain. You're testing judgment, not just knowledge.

For example:

  • "Our model performs well in testing but degrades after two weeks in production. Walk me through how you'd diagnose that."
  • "A stakeholder wants to use the model's output to make a financial decision. What would you need to validate before you'd be comfortable with that?"
  • "We have class imbalance in our training data. How would you approach that, and what are the tradeoffs of each method?"

Candidates who give structured, nuanced answers to questions like these have usually shipped something real.

Problem-solving exercises

A take-home project is worth more than any technical interview question. It shows how a candidate approaches ambiguity, how they communicate their reasoning, and whether they can deliver something usable rather than just something that runs.

Keep the scope tight — three to four hours, not a week. The goal is not to get free work out of candidates. It's to see how they operate when no one is watching and the requirements aren't spelled out.

Example briefs:

  • "Here is a CSV of customer support tickets from a SaaS product. Build a simple classifier that routes tickets to the right team. Document every assumption you made about the data and explain why you chose the approach you did."
  • "Here is a set of 200 product descriptions in varying quality. Build a pipeline that normalizes and enriches them using an LLM. Include a note on how you would evaluate whether the outputs are good enough to ship."
  • "Here is a broken RAG implementation that retrieves irrelevant chunks most of the time. Diagnose the problem, fix it, and explain what you changed and why."

What you are evaluating is the quality of their decisions, not just the output. A candidate who delivers a clean solution with no explanation of their reasoning is less valuable than one who delivers something imperfect and can clearly articulate where they would take it next.

AI collaboration assessment

If you're hiring generative AI developers, evaluate how they use AI tools as part of their process. A candidate who has never integrated an API, built a RAG pipeline, or thought carefully about prompt behavior in edge cases is not a generative AI developer regardless of what the resume says. Also watch for over-reliance on AI assistance as a substitute for actual understanding. That pattern tends to collapse under production conditions.

For example, ask:

  • "Walk me through a prompt you've engineered for a real task. What decisions did you make and why?"
  • "What happens when the model ignores the prompt? How do you test for that?"
  • "Tell me about a time an LLM produced a confident but wrong answer in your system. How did you catch it?"

Candidates who have concrete answers to these questions have actually worked with LLMs outside of a demo environment.

The general problem is that new engineers trust the model too much. They take things for granted, and only people with previous experience distrust it in the right places. But for people who haven't coded without LLMs, it's like a cheat code on the exam. Your brain stops working because you just run whatever it generated. This is a huge liability, because yes, coding benchmarks are getting better, but if you ask it to work with something which was launched like a year ago, you're really going to struggle, because LLMs didn't learn to code — they were manually fine-tuned by people to solve some tasks.
Vitalijus Cernej
Vitalijus Cernej
Lead ML Engineer
Share
Share on X
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Behavioral questions

Technical skill alone does not make a reliable team member. An AI engineer who cannot communicate with stakeholders, adapt when requirements change, or give and receive feedback clearly will slow a project down regardless of how strong their model work is. These questions are not filler — they reveal how a candidate operates under real conditions.

For example, ask:

  • "Tell me about a time a model you built didn't perform as expected in production. What did you do?"
  • "How have you explained a model's limitations to a non-technical stakeholder?"
  • "Describe a project where the requirements changed significantly mid-build. How did you handle it?"
  • "What do you do when you disagree with a product decision that affects the AI system you're building?"

Pay attention to whether they talk about outcomes and lessons, or just describe what happened. Candidates who reflect on what they would do differently are usually the ones who have actually learned from it.

Live task with screen share

Theory-based interviews have a ceiling. Candidates can answer almost any conceptual question with enough preparation — or with a browser tab open in the background. A short live task under screen share cuts through that.

The task does not need to be complex. Something that a competent engineer should be able to work through in 15 minutes using their own knowledge and basic problem-solving is enough. The point is to observe how they think in real time: do they read the error message before reaching for a tool, do they ask clarifying questions, do they know when to stop and reassess?

It's very hard right now to perform interviews because people tend to screen share and you can answer most theoretical questions by just using ChatGPT. But we do have online coding tasks with screen share, and one of the things which is really surprising — no one from us expected it — is that we give tasks which are really trivial if you can just Google and use your brain. This is a 15-minute task, honestly nothing crazy. From all of our interviews, more than 90% fail with it. And from the people who have used LLM support to solve it, not a single person has solved it, because every time you throw this task at an LLM, it just creates another task which they again throw at an LLM to debug, and it's just a rabbit hole.
Vitalijus Cernej
Vitalijus Cernej
Lead ML Engineer
Share
Share on X
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Scope the Project Before You Hire

One of the most common ways AI hiring goes wrong is that the project scope is undefined when the engineers start. You bring someone in, they build something, and then three months later you realize what was built does not match what was needed because nobody agreed on what "done" looked like.

Before you hire gen AI developers for a custom product, nail down the following:

  • What problem does this solve, and how will you measure that it's solved?
  • What data do you have, and what is its current quality?
  • What are the security and compliance requirements?
  • Who owns what parts of the project?
  • What does the delivery timeline look like, with actual milestones?
  • What is the budget, and how is it structured?
  • What are the acceptance criteria for each deliverable?
  • How will scope changes be handled?

This is not bureaucracy. This is the difference between a project that ships and a project that stalls at 80% for six months while everyone argues about what was agreed.

A written scope document that covers these elements forces alignment before the first line of code is written. It also gives you a basis for evaluating candidates, because people who ask good questions about scope during the interview process are usually people who have seen projects fail without it.

Where to Find the Right People

Job boards will get you volume. They will not reliably get you the right candidates for specialized AI roles.

The most effective sourcing channels for AI talent are GitHub (look at what they've actually built), open-source project communities, specialized Discord and Slack communities organized around specific tools or research areas, academic networks for research-oriented roles, and vetted talent networks that vet for AI-specific skills.

For custom AI product work, agencies that specialize in AI development are often faster and more reliable than a pure hiring play. The project gets a team that has built this before, with established practices around data handling, model evaluation, edge case management, and production deployment.

If you are weighing that option, our guide on how to hire an AI agency covers what to look for and what to avoid. Whether you hire a developer directly or engage a development partner, the questions you ask and the standards you hold should be the same.

Transparency Is Not Optional

When you hire AI developers for production systems, especially in regulated industries, the ability to explain how a model makes decisions is a technical requirement, not a nice-to-have. Hiring engineers who treat model interpretability as someone else's problem is a risk. Bias audits, explainability tooling, and responsible data handling should be part of how your AI team operates, not afterthoughts introduced when a compliance team asks uncomfortable questions.

Screen for this explicitly. Ask candidates how they have approached fairness in a past project. Ask how they would explain a model failure to a business stakeholder. Ask what they do when a model performs well in testing and poorly in production. The answers tell you a lot about how they think.

Verifying a Development Partner

If you are evaluating agencies rather than individuals, the due diligence process is similar. Look for consistent evidence of problem-solving, delivery against real business goals, and honest communication when things got difficult. Client reviews on platforms like Clutch verify that past clients actually exist and actually had the experience described.

Red flags to take seriously: vague claims about AI capabilities with no case studies behind them, pricing that cannot be explained with reference to actual scope, and reluctance to discuss how they have handled project failures. Every team that has shipped real AI products has a failure story. Teams that claim otherwise have not shipped much.

Closing Thoughts

Getting AI development right starts long before the first interview. It starts with defining what you are building, why it matters, and which roles are actually required to build it well. Once that foundation exists, hiring becomes a structured process rather than a series of best guesses.

A few things that are worth holding onto:

Map the roles you need against the actual work, not against titles you have seen elsewhere. Write job descriptions around outcomes, not just technologies. Test for judgment and judgment under real conditions, not just technical knowledge in the abstract. Define scope in writing before anyone writes code.

The companies that build AI products with real ROI are not the ones that hired the most aggressively or moved the fastest. They are the ones that knew what they needed and were deliberate about how they got it.

Hiring One Partner For All AI Roles

We have built over 150 AI products for clients including FanDuel, Consumer Reports, Experian, and SimpliSafe. Our team of PhD-level engineers and certified product managers has been doing this for eight years, and we have been ranked alongside Microsoft, NVIDIA, and IBM as a top 5 AI consultancy.

If you are figuring out how to hire a developer for your AI project, or trying to build the right team structure before committing to a major build, we can help you think it through.

Schedule a free discovery call with our founders. We will not hand you off to a sales team. You will talk directly to the people who have built projects like yours.

Book a discovery call with NineTwoThree

Alina Dolbenska
Alina Dolbenska
Content Marketing Manager
Alina Dolbenska
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