On Software Engineer interview questions & guide 2026

Interview questions at On are designed to probe your technical depth, your ability to handle real-world complexity, and your alignment with the company’s fast-moving culture. While specific questions vary by team and seniority, you should be prepared for a mix of practical coding, architectural thinking, and behavioral reflection.

Technical & Domain Knowledge

These questions evaluate your proficiency in your primary tech stack and your ability to apply engineering best practices to real-world scenarios.

• How do you debug production systems?
• Can you explain middleware in Node.js and dependency injection in NestJS?

Preparation at On should focus on demonstrating both your technical mastery and your ability to function as a collaborative team member. The interviewers are looking for engineers who can move fast without sacrificing quality.

Role-related knowledge – You must be prepared to discuss your chosen tech stack in detail. Interviewers value candidates who understand not just how to use a tool, but why it is the right choice for a specific problem. Be ready to explain your past architectural decisions.

Problem-solving ability – You will be tested on your ability to break down large, ambiguous problems into manageable technical tasks. Approach these with a structured mindset; always clarify constraints before jumping into a solution.

Communication & Collaboration – On values people who can work across functions. In interviews, explain your thought process clearly, listen to feedback from the interviewer, and show that you consider the impact of your code on product managers and other stakeholders.

The interview process at On is known for being thorough and occasionally lengthy, reflecting the company’s commitment to finding candidates who truly align with their high-performance culture. You can expect a sequence that includes a recruiter screening, technical assessments (ranging from live coding to take-home projects), and multiple rounds with cross-functional stakeholders including hiring managers, product owners, and engineering leadership.

The company values a "conversational" interview style, where the goal is to get to know you as a potential colleague rather than just a technical asset. However, be prepared for significant rigor in the technical rounds. Communication can sometimes be slower than expected, and you should be proactive in tracking your progress through the stages.

This visual timeline highlights the progression from initial screening to final cross-functional panels. Candidates should interpret this as a multi-week commitment that requires consistent energy management and preparation. Because processes can vary based on the specific team or seniority level, use this structure to plan your availability and keep an open line of communication with your recruiter.

Technical Proficiency

This evaluates your core development skills. You are expected to demonstrate fluency in your primary language and a strong grasp of data structures and algorithms.

• Code Quality – Writing clean, maintainable, and well-tested code.
• Debugging – Showing a systematic approach to identifying and resolving production issues.
• Tooling – Proficiency with frameworks relevant to the role (e.g., NestJS, Salesforce, etc.).

As a Software Engineer at On, your primary responsibility is to deliver high-quality, scalable code that supports the company's ambitious growth. You will be expected to own features from the design phase through to production, ensuring that your work meets both technical standards and user needs.

Collaboration is at the heart of the role. You will work closely with product managers to define requirements, with operations teams to ensure system reliability, and with other engineers to conduct code reviews and architectural discussions. You are expected to be a self-starter who identifies technical debt or process inefficiencies and proactively proposes solutions to address them.

A strong candidate for a Software Engineer position at On combines a solid engineering foundation with the agility to work in a fast-growing, dynamic environment.

• Must-have skills:

  • Proficiency in modern backend or full-stack technologies.
  • Strong understanding of data structures, algorithms, and OOP.
  • Experience working in collaborative, agile environments.
  • Excellent communication skills to bridge the gap between technical and product teams.

• Nice-to-have skills:

  • Experience with e-commerce platforms or large-scale retail operations.
  • Familiarity with cloud-native infrastructure and CI/CD pipelines.
  • Experience with specific platforms like Salesforce or specialized frameworks mentioned in the job description.

Q: How long does the interview process usually take? The process can be quite comprehensive and may span several weeks to a couple of months. Expect 5–8 sessions depending on the role.

Q: What is the best way to prepare for the technical rounds? Practice standard algorithm and data structure problems, but also focus on practical, real-world coding—like debugging a snippet of code or building a small service—as these are common at On.

Q: How can I stand out during the interview? Show genuine interest in the product and the company’s mission. Candidates who ask thoughtful questions about the team’s strategy and current technical challenges often leave a strong impression.

Q: What should I do if the interview process feels slow? Stay proactive. Send polite, concise follow-up emails to your recruiter to request status updates, but keep in mind that the process is thorough by design.

• Own your narrative: Be prepared to talk about your past projects in detail. Focus on the "why" behind your decisions and the impact of your work.
• Prepare for ambiguity: You may be asked to solve problems with limited information. Use this as an opportunity to show how you gather requirements and define scope.
• Focus on the product: On is a product-first company. Always relate your technical solutions back to the user experience or business value.
• Research the stack: Ensure you are deeply comfortable with the technologies listed in your specific job description.

Joining On as a Software Engineer offers the unique opportunity to influence the technology stack of a global performance brand. The interview process is rigorous, but it is designed to ensure that you are set up for success within a collaborative and high-impact environment. By focusing on your technical fundamentals, architectural thinking, and ability to communicate clearly across teams, you will be well-positioned to succeed.

You can explore additional interview insights, practice questions, and preparation resources on Dataford to further refine your strategy. Preparation is the most effective way to navigate the complexity of the process and demonstrate your value to the hiring team.

The compensation data provided above offers an overview of market ranges for this role. Candidates should interpret these figures as estimates that vary based on experience, specific location, and the seniority of the position. Use this information to benchmark your expectations and prepare for salary discussions with your recruiter.