Interview Guide for BackEnd & Full-Stack Engineering

General Info

We will ask you to complete 3 problems within 90 min timeline. You will have 20 minutes to complete section 1, and then 70 minutes to complete both sections 2 and 3.

• General knowledge questions [15 multiple-choice questions]:

  1. Testing Techniques

  2. System Design

  3. Microservices

  4. REST API

  5. Problem-Solving

• Coding problems related to:

  1. Algorithms & Data structures

  2. REST APIs

• Make sure you finalize your work before moving to another problem.

• Once you complete a section you won’t be able to go back.

• Don’t forget to submit your solution before time expires.

A few things to cover before you start

• Familiarise yourself with the Hackerrank environment first so you can do your best on the day. Make sure you check both sections, before and during the interview. The goal is to eliminate any unnecessary surprises. We want you to focus only on the task at hand.

• Our interview problems are language agnostic so make sure you use your strongest coding language.

• The tasks are timed so make sure you set your working environment accordingly and you won’t be disturbed.

• A significant percentage of your success will rely on system familiarity. It may be a good idea to do a warm-up task beforehand so you are in the right frame of mind and have a good understanding of how everything works.

This is no secret but the interviewing environment is slightly different from your day-to-day work. With this in mind, make sure you will spend some time on preparation. Those who practice, perform better.

Take a look at the Interview Preparation Kit and warm up a little before your big day.

The coding interview is based on the home task sent to you by your recruiter. You are asked to send your solution back to us (your recruiter or coordinator).

During the interview, the conversation will start with a short introduction. After that, we will move to the technical part of the interview where we will be reviewing a coding solution you submitted before the interview. Using your strongest programming language, we will ask you to complete a couple of tasks (extensions) related to the original problem and explain your thought process.

Worth remembering

• Address all requirements in the task;

• Cover test coverage for happy and sad paths; 

• Be ready to share your screen during the interview;

• Send your solution back to us at least 48 hours before the interview.

Interview Structure

Solution walkthrough | 10 – 15 min |

This part focuses on your introduction to the submitted solution. We would like you to explain your thought process during our interview, and any considerations or alternative options you had in mind when working on it.

Extension work – Live coding part | 25 – 30 min | 2-3 tasks 

Come with your solution set up in your preferred development environment, ready to work on extending it. We will ask you to complete a couple of tasks that build upon the code you submitted so you can show your coding skills, specifically back- end coding skills. We suggest you brush up on those to make your skills shine during the interview. We don’t expect you to complete the entire task, but keep the time in mind.

Assessment rubrics | What interviewers look at: 

Coding – try to complete the tasks by using the framework of your choice to its full potential.

Problem-Solving – as there is a time limit associated with this interview, try to get the main task accomplished even if it means you’re not producing the best code. Be sure to communicate this.

Communication – Ask questions, and discuss your thoughts or any problems you’re having. Engineering is collaborative – so is the interview.

Testing – testing code is important and something we do at Deliveroo. Show us how you do testing or talk through it if there isn’t enough time. 

We are interested in learning how you work and solve problems therefore we expect this submission to be fully done by yourself. In this instance we say no to AI – all AI-generated submissions will be rejected.

The following are not allowed during a live coding interview:

• Ask ChatGPT or similar to explain compiler or runtime errors or write code.

• Use Copilot or similar to explain or generate code

During the interview, you’ll meet with one of our Engineers who will give you a problem to solve.

• The interview will be in the same HackerRank environment as your initial technical screen.
• Communicate your thought process as you work through the problem.
• We want to see how you tackle and solve difficult problems.
• You don’t need to solve the entire problem, but show your approach.

Try the Sample Interview

Note: We use AI tools extensively at Deliveroo but we would like to see how you perform in the context of the interview without using them.

Interview Structure:

• Short Intro (5 mins)
• Live Coding session (50 mins)
• Short Outro and Questions (5 mins)

LIVE CODING

Worth remembering:

• Join via the Google Meet link, the interviewer will share the code pair link with you on the call
• Go with your strongest coding language
• Give feedback and communicate throughout

Before the interview:

Take a look at the toolbox, familiarise yourself with the format and environment. Please use one of the following supported browsers for HackerRank interviews:

Mozilla Firefox – Fully supported
Google Chrome – Fully supported
Safari – Partially supported*
Edge –  Fully supported

*Zoom audio and video calls inside HackerRank interviews are not supported in Safari

During the interview:

• Explain your logic and give feedback, keep communication going throughout
• Avoid using AI tools for assistance to solve the problem as this does not show us your capabilities

After the interview:

Your recruiter will liaise with the interviewers and be in touch with the outcome of the interview.

Toolbox | Preparation kit:

Getting Started with HackerRank Interviews
Interview Preparation Checklist for Candidates
FAQs on HackerRank interviews

The goal is a design you could hand off to an engineering team. As you would in real work, consider requirements, production challenges, edge cases, and describe how you’d address them. We avoid trick questions, and there are many valid ways to solve the problem. Choose an approach based
on your experience and intuition, and be prepared to explain your reasoning and the tradeoffs you’re making.

Interview Structure:

• Short intro (5 mins)
• Designing (~45 mins)
• Outro and Questions (5-10 mins)

Before the interview:

• Get comfortable with a whiteboard. Use tools like draw.io  or Excalidraw  to visualise system components and their interactions.
• Reflect on past designs. Think about challenges you faced, the approaches you took, and decisions you might revisit in hindsight.
• Review fundamentals. Be ready to discuss core system design patterns, data persistence, communication mechanisms, system constraints, and
  production considerations.
• Practice! Time-box yourself with sample design questions and, if possible, do mock interviews or ask for feedback to uncover blind spots.

During the interview:

• Collaborate with the interviewer. Lead the design but treat the session as a discussion. Explain your thinking, listen to prompts, and consider
  suggestions–they  may  highlight important  areas  you  haven’t  considered.
• Use your time effectively. You’ll have ~40 minutes. Clarify requirements quickly, start with a high-level design, note risks, and refine iteratively. Monitor your pace to avoid feeling rushed.
• Workincrementally.  Break  the  system  into  parts  and solve  each  thoroughly  before moving on. Iteratively improve the design as new
  considerations emerge.
• Stick to what you know. Choose familiar technologies and be ready to justify them. A simpler, solid solution with known limitations is better
  than a complicated one you can’t explain.
• Think about production. Design for scale, reliability, and failure modes. Discuss edge cases and how you’d gain confidence in the system
  before rollout.

Note:  We use AI tools extensively at Deliveroo but we would like to see how you perform in the context of the interview without using them

Tips and Tools for Success

• Think out loud:  Explain your reasoning and tradeoffs.
• Start high-level: Outline the big picture before diving into details.
• Keep it simple:  A clear, solid design beats an over-engineered one.
• Ask questions:  Clarify requirements early.
• Iterate: Refine as new constraints or edge cases appear. Focus on production: Consider scale, reliability, and failure modes.
• Practice with whiteboarding tools: draw.io,Excalidraw

This interview looks at how you handled specific challenges in the past to assess if you will be a good match for the role. Some of the areas we address are:

• Communication 

• Team management 

• Leadership 

• Problem-solving

• Flexibility and can-do attitude Initiatives and growth mindset

• Organisation and self-development 

• Decision making

We care about our culture as much as we care about our products! Have a look at our Deliveroo Values

Live and breathe our marketplace 

Being deeply immersed in all sides of our marketplace, and each and every neighbourhood we serve.

Play to win

Setting bold targets and seeing them through with tenacity, creativity and grit.

Celebrate difference

Advocating for respect and fairness for everybody, understanding we are all individuals on a unique journey.

Champion big and small innovations 

Innovating no matter what our role is, and celebrating achievements no matter the size.

Obsess about operational excellence

Leaving things better than we found them, investing both our time and money in the things customers care about.

Be curious and intellectually honest

Thinking deeply and debating each other with respect while keeping our biases in check. 

Take a look at our few examples

Tell us about a time when you failed to meet a deadline. What did you fail to do? What did you learn? (Before answering have a think about)

• The root cause.

• Why did it seem like a good idea at the time? 

• How did you apply what you learned afterwards?

Describe to us a specific task or a challenge that you were facing and how you made sure in successfully completing it. What were the key factors of this success? (Before answering have a think about)

• Be clear up front about your objectives and wider context.

• Reasons you chose those particular strategies and tools to complete it.

• Any measures you had in place to monitor your progression?

• Main obstacles that you had to address and things learned along the way.

Provide an example of the time when you had a difference of opinions with one of your colleagues regarding a project you both worked on and how did you arrive at the conclusion. (Before answering have a think about)

• Specify the situation, differences of opinions and other important context. 

• What data, tools or information you used to support your idea?

• How this discussion ended and impacted your future cooperation?