Type · motivation
Undo helps companies understand their software's performance and reliability. What interests you about working on a product that provides deep technical insights into other companies' applications?
How to Pass the Undo Software Engineer Interview in 2026
Growth · Software Engineer Interview Guide
Headquartered in United KingdomInterview language: English
The Undo DNA (TL;DR)
The 'Precision Engineering' value at Undo drives the interview loop, assessing a candidate's ability to design resilient systems and deeply understand failure modes. Interviewers look for clear articulation of technical trade-offs, especially when discussing the architecture behind features like the ReplayEngine.
The Undo Interview Loop
Your onsite loop will typically consist of 5 rounds.
- 1
Round 1
Recruiter ScreenMotivation, role fit, logistics. - 2
Round 2
Coding ScreenLeetCode-medium algorithmic problems under time pressure. - 3
Round 3
System DesignDistributed systems, trade-offs at scale, architecture under constraints. - 4
Round 4
Onsite CodingLeetCode-hard problems, reasoning about defects, code clarity, edge cases. - 5
Round 5
Behavioral / LeadershipPast evidence of ownership, influence, resolving conflict.
The Danger Zone: Top Reasons Candidates Fail
Based on our database of Undo interview outcomes, avoid these common traps:
- Storing every single trace, leading to unmanageable storage costs.
- Failing to address memory constraints, e.g., by storing all historical data.
- Focusing only on the technical details without considering the business impact.
- Not considering different sampling strategies (head-based, tail-based, adaptive).
Test Yourself: Real Undo Questions
Three real prompts pulled from our database.
Type · algorithmic
Undo's product needs to efficiently query historical performance data. Imagine you have a dataset of millions of events, each with a timestamp and a duration. Implement a function that, given a time range and a maximum duration, returns the count of events within that range and duration. Optimize for read performance.
Type · learning
STARUndo operates in a rapidly evolving space (observability, distributed systems). Tell me about a time you had to quickly learn a new technology or complex system for a project. How did you approach the learning process, and what challenges did you face?
+ many more questions, signals, and worked examples
Sign up to unlock the full Undo grading rubric
Undo Interview Question Bank
A sample from our database, grouped by round. Sign up to see the full set.
9 of 13 questions shown
1
Recruiter Screen
1- 1
Type · motivation
Undo helps companies understand their software's performance and reliability. What interests you about working on a product that provides deep technical insights into other companies' applications?
2
Coding Screen
3- 2
Type · algorithmic
Given a stream of user requests to a SaaS application, design an algorithm to detect and report potential performance regressions. For example, if the average response time for a specific API endpoint doubles over a 5-minute window, flag it. Assume you have limited memory. - 3
Type · algorithmic
Undo's product needs to efficiently query historical performance data. Imagine you have a dataset of millions of events, each with a timestamp and a duration. Implement a function that, given a time range and a maximum duration, returns the count of events within that range and duration. Optimize for read performance. - + 1 more questions in this round (sign up to unlock)
3
System Design
3- 4
Type · design
CIRCLESDesign a system for Undo that ingests and processes high-volume telemetry data (metrics, traces, logs) from thousands of customer applications in near real-time. Consider data ingestion, storage, querying, and aggregation. - 5
Type · design
CIRCLESUndo needs to provide its customers with the ability to set up alerts based on complex conditions across their performance data (e.g., 'alert if P99 latency of /api/v1/users endpoint is > 500ms for 10 minutes AND error rate > 5%'). Design the alerting system, including rule definition, evaluation, and notification. - + 1 more questions in this round (sign up to unlock)
4
Onsite Coding
3- 6
Type · debugging
Root Cause Analysis (Issue Tree + 5 Whys)A customer reports that Undo's dashboard is showing inconsistent data for their service's error rate. Here's a simplified version of the data processing code. Find the bug and explain how you'd fix it. - 7
Type · algorithmic
Implement a function to calculate the 'time to recovery' (TTR) for a given service, based on a stream of events indicating service availability or downtime. TTR is the duration between the start of an outage and the moment the service is fully restored. Handle intermittent failures and ensure accuracy. - + 1 more questions in this round (sign up to unlock)
5
Behavioral / Leadership
3- 8
Type · ownership
STARTell me about a time you identified a significant technical problem or opportunity in a project that wasn't explicitly assigned to you. What did you do, and what was the outcome? - 9
Type · collaboration
STARAt Undo, we prioritize precision when debugging complex distributed systems. Tell me about a time you had to advocate for a specific architectural trade-off that prioritized long-term system stability or observability over a faster time-to-market. How did you communicate the technical risks to stakeholders who were focused on immediate feature delivery? - + 1 more questions in this round (sign up to unlock)
Unlock all 13 Undo questions, free
No credit card. Every question with its framework, the grading signals interviewers score against, and a worked answer for each.
Interview tracks at Undo
How Undo's DNA translates across functions. Pick your role.
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Practice Undo interviews end-to-end
Undo Mock Interview
Run a live mock interview with our AI interviewer using Undo-style prompts. Get scored on structure, signal, and answer length - exactly how the real loop grades you.
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STAR Stories for Undo Behavioral Rounds
Build a Story Bank of your past wins, mapped to the leadership signals Undo interviewers grade on. Reuse them across every behavioral round.
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Undo Interview Prep Hub
The frameworks behind every Undo round: CIRCLES for product sense, hypothesis-driven debugging for analytical, STAR for behavioral. Learn each one in 10 minutes.
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Interview Frameworks
CIRCLES, STAR, AARRR, RICE, MECE. The exact frameworks that make Undo interviewers nod instead of frown. Step-by-step playbooks with the moves and the pitfalls.
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Sample answers
What a strong answer to these Undo interview questions shows.
Undo helps companies understand their software's performance and reliability. What interests you about working on a product that provides deep technical insights into other companies' applications?
A strong answer shows: Understanding of Undo's market and customer problems.; Enthusiasm for technical challenges and problem-solving.; Alignment with company values and mission..
Undo's product needs to efficiently query historical performance data. Imagine you have a dataset of millions of events, each with a timestamp and a duration. Implement a function that, given a time range and a maximum duration, returns the count of events within that range and duration. Optimize for read performance.
A strong answer shows: Knowledge of efficient data structures for range queries.; Ability to optimize for read performance.; Understanding of time-based data processing..
Frequently asked questions
How long does the Undo interview process take?
Most candidates spend between 4 and 8 weeks from recruiter screen to offer. The onsite loop itself runs in a single day or is split across two half-days, with debrief and offer typically within 5 business days after.
How should I prepare specifically for Undo?
Focus on three things: (1) the company DNA shown above - what they actually grade for, (2) the rounds in your loop, especially the round most candidates underestimate, and (3) drilling on the question types in this guide using a structured framework like CIRCLES or STAR.
Does this apply to engineering or design roles at Undo?
The DNA stays the same - what changes is the round mix. SWE candidates face coding screens instead of Product Sense; designers face portfolio reviews and design exercises. The "what they value" and behavioral signals carry across all functions.
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