Good technical interview preparation is less about memorising answers and more about practising the right things out loud. Interviewers want to see how you think, how you communicate and whether you understand the fundamentals of the role. A candidate who reasons clearly through a problem they can't fully solve often does better than one who silently writes a perfect answer.
Preparation also looks different depending on the role. A backend engineer may face coding problems and a system design chat. A data analyst may get a SQL exercise and a case study. A technical support candidate may be asked to troubleshoot a scenario. Start by working out what your interview will actually include.
This guide walks you through the common stages, how to prepare for each, and what to do on the day.
What happens in a technical interview?
Every company runs its process differently, but most include some of these stages:
- Screening call: a short conversation with a recruiter or hiring manager about your background, interest and availability.
- Technical assessment: an online test, a take-home assignment or a timed coding exercise.
- Technical interview: a live session where you solve problems, discuss your projects or answer role-specific questions.
- Behavioural interview: questions about how you work with others, handle problems and learn.
- Final conversation: often with a senior manager, covering fit, expectations and sometimes salary.
Smaller companies may combine several of these into one or two conversations. Ask the recruiter what to expect. It is a normal question, and the answer tells you exactly what to prepare.
How to prepare by role
Developers (frontend, backend)
- Review the fundamentals of your main language: data types, functions, loops, error handling and how it handles asynchronous code.
- Practise short coding problems involving arrays, strings and dictionaries. For backend and larger companies, add more data structures and algorithms.
- Be ready to explain how the web works: HTTP requests, APIs, databases and, for frontend, the DOM and browser rendering.
- Know your own projects inside out.
Data analysts
- Practise SQL queries: joins, grouping, filtering and window functions.
- Brush up on Excel or spreadsheet skills and your visualisation tool.
- Prepare to interpret a chart or dataset and explain what it means for the business.
QA, DevOps, security and support
- QA: practise writing test cases for an everyday feature, such as a login page, and explain how you'd report a bug.
- DevOps / SRE: be ready for Linux commands, networking basics, CI/CD, containers and how you'd investigate a slow or failing service.
- Security: review core concepts like authentication, common web vulnerabilities (the OWASP Top 10 is a good reference) and basic networking.
- Technical support: practise troubleshooting scenarios out loud and explaining technical issues in plain language.
A practical way to find your gaps is to try TechDNA's role challenges. Each is a 20-question knowledge test for a specific role and level, and your results show which topics need more work.
How to talk through a problem
Live problem-solving is where many beginners struggle, not because they lack knowledge, but because they go quiet under pressure. A simple routine helps:
- Repeat the problem in your own words. This confirms you understood it and buys you thinking time.
- Ask clarifying questions. What is the input? Can it be empty? What should happen with invalid data?
- Work through a small example by hand before writing any code.
- Describe your approach before you start. Start with a simple solution, even if it is not the most efficient.
- Write the code, talking as you go. Explain what each part does.
- Test it. Walk through your example and an edge case.
- Discuss improvements. If there's a faster or cleaner approach, mention it, even if you don't have time to implement it.
If you get stuck, say so and explain what you're considering. Interviewers often give hints, and how you use a hint is part of what they're assessing.
How to handle take-home assignments
Take-home tasks are common for junior roles. They test whether you can produce clean, working output on your own.
- Read the brief twice and note every requirement.
- Ask questions early if something is unclear.
- Keep it simple and finished. A small, working solution beats an ambitious, broken one.
- Write a clear README explaining how to run it, the decisions you made and what you'd improve with more time.
- Respect the time limit. If they suggest a few hours, don't spend a week; it can raise questions about how you'd work under real deadlines.
Plan around power and internet. If a deadline is tight, charge your devices in advance, save often and push your work to GitHub regularly.
Preparing for behavioural questions
Technical skill gets you considered; behaviour often decides the offer. Expect questions like:
- "Tell me about yourself."
- "Why do you want this role?"
- "Tell me about a time you solved a difficult problem."
- "Tell me about a time you made a mistake."
- "How do you learn something new?"
Use the STAR method to structure answers: Situation, Task, Action, Result. Career switchers have an advantage here. Your experience in banking, teaching or customer service gives you real stories about pressure, people and problem-solving. Our guide on communication skills for tech jobs has more on presenting yourself clearly.
A simple two-week preparation plan
If you have an interview coming up, here's a structure you can adapt:
- Days 1 to 3: Research the company and role. List the skills in the job advert and rate yourself honestly on each.
- Days 4 to 8: Practise the weakest skills daily. Do short problems, SQL queries or troubleshooting scenarios, depending on your role.
- Days 9 to 11: Rehearse explaining your projects and your career story. Record yourself or practise with a friend.
- Days 12 to 13: Do a mock interview, timed, out loud.
- Day 14: Rest, check your setup and prepare questions to ask the interviewer.
What to do on the day
- For remote interviews: test your camera, microphone and internet beforehand. Have a backup, such as mobile data or a charged power bank, in case power or broadband fails.
- Have water, a pen and paper nearby for working through problems.
- Arrive or log in early.
- Prepare two or three questions to ask, such as "What does success look like in the first three months?" or "How does the team review code?"
- Be honest about what you don't know. "I haven't used that, but here's how I'd find out" is a perfectly good answer.
After the interview
Send a short thank-you message if you have the interviewer's contact. Then write down what went well and what you struggled with while it's fresh. Every interview, including the ones that don't lead to an offer, is practice for the next one.
Frequently asked questions
How long should I prepare for a technical interview?
It depends on your current level and the role. If you're already comfortable with the fundamentals, one to two weeks of focused practice is often enough to sharpen up. If you're still learning core concepts, you'll need longer, so start practising interview-style questions well before you apply.
What if I can't solve the problem in the interview?
That happens to many candidates, and it is not automatically a failure. Keep talking through your reasoning, try a simpler version of the problem, and use any hints you're given. Interviewers are often assessing your approach as much as the final answer.
Can I use Google or AI tools in a technical interview?
Only if the interviewer says so. Some take-home tasks allow any resources, while live interviews usually don't. Always ask, and be ready to explain every line of anything you submit.
What should I wear for a remote tech interview?
Tech companies are often relaxed about dress, but neat and comfortable is a safe choice. More importantly, choose a quiet spot with good lighting and a stable connection.
Interviews get easier with practice, and so does knowing what you're good at. If you're still choosing the role to prepare for, take the free TechDNA assessment and see where your strengths fit best.