The Tech Interview Behind the Scenes: Anton Lelios

The Tech Interview Behind the Scenes is an HRLabs series.
Let’s take a look behind the scenes of the technical interview process from the interviewers' perspective.
Our goal is to provide candidates with valuable tips and recommendations directly from professionals who conduct interviews for various technical roles.

“It's important to give a chance because sometimes first impressions are wrong.” shares Anton Lelios, founder and CEO of the Viking Rabbit.

Tell us more about your career path.

If I had to describe it in two words, I’d say – steep and uncomfortable. It’s the result of a combination of my workaholism and the incredible luck of finding myself, from the very beginning, in an extremely dynamic environment – with a vacuum to fill and surrounded by people with a similar mindset and a desire to improve every single day.

The circumstances unfolded in such a way that, on my very first project, from a team of 6–7 people, after just a few months, only the product manager and I were left. The product manager, at the same time, was responsible for a much larger and higher-priority project. Whether I wanted to or not, I had to take on the roles of Fullstack Developer, QA, and Customer Support. After a few months, the project’s metrics improved drastically. Whether it was because of my work or a change in Google’s algorithm – we’ll never know. Either way, the company owners decided to reinvest in it. They added new people to the team, and since I had become the person with the most knowledge about the project, they made me the Lead.

Things continued to progress in a similar way moving forward. I was fortunate that new opportunities kept arising, I was the most suitable person for the job, and I was ready to dive into the deep end. I was definitely outside my comfort zone almost constantly, but I put in a lot of work and effort and had the support of incredible professionals who believed in me and mentored me.

This is how I progressed through roles like Tech Lead, Team Lead, Head of Backend Solutions, Technology Manager, and Engineering Manager, and now I’m working on building my own startup. I’ve mentored dozens of people (including managers), been responsible for technological standards in three different companies, built and scaled several successful teams, and, perhaps most relevant for this blog – I’ve participated in and led more interviews than I can remember.

As a candidate, have you had any strange interviews? What about interviews that impressed you?

Perhaps the most unusual interview I’ve ever been to was after completing the IT Boot Camp. The interview was conducted with several companies simultaneously, in front of about ten people. It was extremely stressful, and they asked quite uncomfortable questions, such as, “We’re several companies here—who would you like to work for?”

Advice from a candidate in such a situation: Take a sip of water, tell your inner critic to be quiet, and just go for it.

For anyone on the other side reading this: Two interviewers at the same time are the absolute maximum.

What skills and qualities do you look for in a candidate? How can a candidate stand out during the interview?

It’s difficult for me to give a universal answer to this question. There’s a huge variation in needs depending on the position that needs to be filled. For most of my career, I’ve focused more on soft skills because I’ve usually had the luxury of a well-established culture and mentoring processes. As a result, it was enough for me to believe that the candidate had the motivation and potential to acquire the necessary technical skills.

Now that I’m starting my own startup with very limited time and resources, things are quite different. At least in the beginning, I’ll need to look for people with very specific hard skills and experience.

It’s incredibly important, when we want to hire someone, to be brutally honest with ourselves about what our needs are and what we can offer, and to communicate these clearly in job postings and during interviews. Similarly, on the candidates’ side, it’s crucial to gather as much information as possible about what is expected and offered for a given role.

The candidates who have stood out the most were those with whom the “interview” felt more like a conversation than an interview. If you’re genuinely passionate about and understand the work you do, it usually shows, and the conversation naturally becomes engaging and inspiring.

What questions do you typically ask in technical interviews? Do you have specific tasks or problems that you often use to assess candidates?

After the usual small talk to break the ice, my first question is, “Tell me about a problem you recently solved at work.” I’ll refer to my earlier point – if you love what you do and have genuinely solved a problem, you can usually describe it in great detail. Accordingly, if I’m looking for expertise in a specific technology, I’ll ask about a problem you solved using it and dig deeper into specifics, such as particular behaviors, techniques, and why you chose that technology.

From there, it depends on the candidate’s experience:

• For more experienced candidates, I present a comically broad and abstract problem, for example: “You’re starting a new project – you need to build a copy of Twitter/X.” I improvise the details and requirements based on the level of the position, the candidate’s experience, the direction they take, and the questions they ask. Here, I focus on what questions they ask, how they think, and what decisions they make – there’s no right or wrong answer; the process is what matters.

• For less experienced candidates, I aim for a more specific problem solvable with technologies they mentioned they know. My goal here is to determine whether they’ve just memorized the theory or genuinely understood it. A favorite example of mine is asking about the Singleton design pattern. If they know what it is and recite how to implement it, I give them a task that involves a different, less familiar pattern (Multiton). If they understand the “why” and “how” of the first pattern, it’s easy for them to reach a solution. If they don’t know what Singleton is, I explain it and help them arrive at the implementation using concepts they already know.

In both cases, I encourage candidates to think out loud and ask guiding questions to ensure they understand the task and steer them in the right direction.

How important are good communication skills for a candidate? How do they impact the overall interview?

If we can’t find common ground during the interview, in my experience, it’s unlikely that this will change later on.

That said, it’s crucial to remember that being interviewed is a stressful experience. Some positions require the skills to handle such stress, but unless I’m explicitly testing for that, it’s my responsibility as an interviewer to help the candidate feel at ease. There’s a significant risk of mistaking nervousness for a lack of knowledge. To this day, it’s one of the things I pay the most attention to.

I’m sure an entire book could be written on the subject, but in short, here’s what I do:

• I start with small talk and so-called ice-breaker questions to set a relaxed tone.
• When transitioning to technical topics, I begin with things I’m confident the candidate knows, to help them build confidence.
• If they make a mistake, I ask clarifying questions to ensure we’ve understood each other correctly and to give them a chance to recover.
• If they realize they’ve made a mistake, I try to lighten the mood. Bonus points if it’s a self-deprecating joke like, “Honestly, I didn’t know that either.”
• I aim for logical flow in my questions, rather than jumping from one topic to another.
• Most importantly, as I mentioned earlier, I focus on asking about things the candidate has experience withand dive deeper to understand how well they grasp them.

How important is cultural fit when making a hiring decision? How do you assess whether a candidate will fit well into the team?

In one word – huge. Team and company culture is something that takes on a life of its own, regardless of what your website says about "Values, Mission, and Vision," or what we think it is. Culture is perhaps one of the hardest things to build and maintain, and at the same time, the easiest and most certain way to fail is by creating a bad or toxic one.

If you hire people without keeping this in mind, sooner or later, a culture will form, and chances are it won’t be the one you want.

I assess whether a candidate will fit by asking for specific examples of how they’ve reacted in certain situations, while avoiding hypothetical questions.

It’s very important to remember that this is a two-way process. We spend about one-third of our lives at work. I can hardly think of an easier way to make your life miserable than working in a place where the culture doesn’t suit you. Unfortunately, life sometimes forces us to make compromises in this regard, but if you’re reading this blog, I’d bet there’s a way to avoid that.

What are the most common mistakes candidates make during an interview? What advice would you give candidates on how to prepare for an interview?

Perhaps the most important thing is to learn as much as possible about the company and the position. If you don’t know what the company does, the requirements for the role, and why you want to work there, your chances of passing the interview (and being happy working there) are close to zero.

Most likely, you can find information online about the company’s tech stack, its culture, how interviews are conducted, the experience of the interviewers, and so on. If you research these things, it’s hard to be caught off guard.

Preparing for the way I conduct interviews is quite simple:

• Read the job description, and if there’s a technology you’re unfamiliar with, do a bit of research about it.This doesn’t mean you should claim in the interview that you know everything about it, but it will prepare you to have a meaningful conversation – “I haven’t worked with X, but I read about it. I’ve used Y, which seems similar. Why did you decide to use X?”
• Take some time to think about a challenging problem you’ve worked on. Bonus points if it involves relevant technologies.
• The rest is about having genuine interest in the work you do or want to do and consistent efforts to become better at it.

Unfortunately, many companies still rely on traditional interview methods with software trivia and live algorithmic programming tasks. For roles where there are hundreds of candidates, this is an understandable approach for initial screening. Personally, I would skip such methods unless it’s for a company of FAANG caliber (Facebook, Amazon, Apple, Netflix, Google). If you have to go through such a process, there’s only one solution – studying theory and practicing tasks on sites like LeetCode.

What advice would you give to candidates who want to improve their technical skills? Are there any resources you would recommend?

Resources are abundant – blogs, elite universities like MIT and Stanford offer their courses online for free, and YouTube is full of high-quality tutorials. ChatGPT can be incredibly useful, especially if you know how to use it, but even without advanced Prompt Engineering skills, you can get excellent results for the basics. Those who truly want to learn will find a way – it just takes proactivity and consistency.

I shared the story about my first project for a reason. I wasn’t left to handle it alone because I was some sort of genius, but because it wasn’t a priority, and this was the cheapest way to keep it afloat. I could have easily spent my days doing the bare minimum, and as long as I didn’t completely ruin it, no one would have cared much. The fact that I put in all that effort, even though no one expected it from me, set me on this successful path. Yes, I was incredibly lucky to be in a place where that was noticed and appreciated, but if I hadn’t acted that way, I certainly wouldn’t have achieved this success.

You need to be proactive, challenge yourself, and seek out opportunities. If your manager helps you with this – great, you’re in the right place. But ultimately, it’s your responsibility because developing your skills benefits you, no matter where you work or what you do.

Share more about the best (or worst) interviews you've conducted.

I’ve probably conducted many bad interviews myself, especially while I was still gaining experience. Interviewing is a skill, and like any other, it requires preparation and practice. Luckily, I’ve had many mentors who helped me along the way. You can’t just throw a programmer into a technical interview and expect good results.

The best interviews have always been when you see the candidate speaking passionately about what they’ve done and genuinely interested in solving the problem you’ve presented. I’ll never forget one particular interview where, after the first 10–15 minutes, my colleague and I exchanged glances, and it was clear to both of us that we were going to make an offer. The remaining 40–50 minutes were pure enjoyment, just seeing how far the candidate would exceed expectations.

The worst interviews, on the other hand, are when you meet someone who’s been doing a job for years, yet it’s clear they’ve neither enjoyed it nor really understood what and why they were doing.

How do you evaluate a candidate during an interview—based solely on their theoretical knowledge, or is their approach to solving a problem/task more important to you? What other factors do you consider when making a decision?

If you can type the question into Google and find the answer in the first line of the first result, I’m not particularly interested in whether you can answer it correctly. Theory is important, but what matters much more is whether you understand it and can apply it in practice. Even more critical is your attitude and approach.

Another key factor is how the candidate will fit into the team and the company. For a team to be successful, it’s important to have people with diverse qualities and experiences that complement each other. You can’t have a team made up entirely of seniors, nor one made up entirely of juniors.

Nobody likes overly critical individuals, but it’s also useful to have people who don’t shy away from providing constructive feedback. Not everyone needs to be the life of the party, but if everyone is an introvert like me, it’s hard for the team to gel. It’s great to have ambitious, driven individuals, but if that’s the dominant trait across the team, it can be challenging to keep them motivated during slower periods.

Balance is key, and as unpleasant as it may be, sometimes the real reason behind a rejection is simply: "We’re sorry, but you wouldn’t be the right fit for the team."

Share a funny story from your experience as an interviewer :)

At my previous company, we had to do interviews the morning after our Christmas party. Mine were online and shorter, so I could recharge during the breaks, but my colleagues had in-person interviews – I think I saw them leave the room twice to refill the water jug.

The other stories aren't exactly funny or worth sharing, but whatever you might think, with enough time, you'll see it – people who don't know why they're there, with exaggerated CVs, angry and arrogant. When you work with people, you can expect literally anything. It's important to give everyone a chance because sometimes first impressions are wrong, and stress manifests differently in different people. However, sometimes the situation is like "Bulgaria doesn't love me, but I'm the greatest," and then it's truly a tragicomedy.

I also have a story from my first interview as a candidate. It was a group interview, maybe 5-6 of us waiting at the same time, and they called us one by one. There was a girl from the company who stayed with us to keep us company and lighten the mood. Her jokes were sarcastic, like "It's really scary inside, you should know. They're big dogs, they chop and hang people." In the end, only two of us remained, and while she went out to finish something, the other candidate went to the restroom. She came back to call him and, when she asked where he was, I joked that after hearing how scary the interview was, he left. A real panic appeared on her face before I burst out laughing and calmed her down. I'm sure if that hadn't happened, my interview wouldn't have gone so well afterwards.