Type · algorithmic

How to Pass the Shopfully Software Engineer Interview in 2026
Growth · Software Engineer Interview Guide
Sign up to see ATSHeadquartered in ItalyInterview language: English
The Shopfully DNA (TL;DR)
The Shopfully 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 Shopfully interview outcomes, avoid these common traps:
- Using overly complex models that are too slow to serve in real-time.
- Proposing a solution that requires scanning the entire dataset for each query.
- Giving a generic answer not specific to Shopfully or the ad tech industry.
- Not considering edge cases like missing properties in user segments or campaign targets.
Test Yourself: Real Shopfully Questions
Three real prompts pulled from our database.
Type · debugging
Type · system-design
+ many more questions, signals, and worked examples
Sign up to unlock the full Shopfully grading rubric
Shopfully Interview Question Bank
A sample from our database, grouped by round. Sign up to see the full set.
9 of 12 questions shown
Recruiter Screen
1- 1
Type · motivation
What interests you about working at Shopfully, specifically within our advertising and growth teams?
Coding Screen
3- 2
Type · algorithmic
Given a stream of user ad impression events (timestamp, user_id, ad_id, click_flag), design an algorithm to calculate the click-through rate (CTR) for each ad in near real-time. Consider memory constraints and potential for high volume. - 3
Type · algorithmic
Implement a function that takes a list of user segments (defined by a set of properties like 'age', 'location', 'device_type') and a list of ad campaigns (each with targeting criteria). The function should return which campaigns a given user would be eligible for. Assume segments and targeting criteria are represented as dictionaries or JSON objects. - + 1 more questions in this round (sign up to unlock)
System Design
3- 4
Type · system-design
Design a system to detect and prevent ad fraud (e.g., click farms, bot traffic) in real-time for a high-volume ad network. Consider data ingestion, feature extraction, model serving, and actioning. - 5
Type · system-design
Design an A/B testing framework for evaluating new ad creatives or targeting strategies on Shopfully's platform. The system should handle traffic splitting, metric collection, and result analysis. - + 1 more questions in this round (sign up to unlock)
Onsite Coding
2- 6
Type · algorithmic
You are given a large dataset of user interactions with ads (view, click, conversion). Design a data structure and algorithm to efficiently answer queries like: 'What is the conversion rate for ad X among users who clicked on ad Y within the last 24 hours?' - 7
Type · algorithmic
Implement a rate limiter for API requests to Shopfully's ad serving endpoint. The limiter should ensure that no more than N requests per user are allowed within a T second window. Consider distributed systems if the service scales across multiple machines.
Behavioral / Leadership
3- 8
Type · behavioral
Tell me about a time you had to make a significant technical decision with incomplete information. How did you approach it, and what was the outcome? - 9
Type · behavioral
Describe a complex bug you encountered in a production system related to ad delivery or user tracking. Walk me through how you identified, diagnosed, and resolved it. - + 1 more questions in this round (sign up to unlock)
Unlock all 12 Shopfully 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 Shopfully
How Shopfully's DNA translates across functions. Pick your role.
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Practice Shopfully interviews end-to-end
Shopfully Mock Interview
Run a live mock interview with our AI interviewer using Shopfully-style prompts. Get scored on structure, signal, and answer length - exactly how the real loop grades you.
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STAR Stories for Shopfully Behavioral Rounds
Build a Story Bank of your past wins, mapped to the leadership signals Shopfully interviewers grade on. Reuse them across every behavioral round.
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Shopfully Interview Prep Hub
The frameworks behind every Shopfully 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 Shopfully 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 Shopfully interview questions shows.
Implement a function that takes a list of user segments (defined by a set of properties like 'age', 'location', 'device_type') and a list of ad campaigns (each with targeting criteria). The function should return which campaigns a given user would be eligible for. Assume segments and targeting criteria are represented as dictionaries or JSON objects.
A strong answer shows: Algorithmic efficiency.; Handling complex matching logic.; Data representation and parsing.; Edge case handling..
A dashboard displaying daily active users (DAU) for different ad campaigns has suddenly started showing incorrect, fluctuating numbers. The backend service aggregates data from multiple sources. How would you approach debugging this issue?
A strong answer shows: Systematic debugging methodology.; Understanding of data pipelines.; Log analysis and monitoring skills.; Root cause analysis..
Frequently asked questions
How long does the Shopfully 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 Shopfully?
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 Shopfully?
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.