Instacart Interview Questions
Practice 87 real Instacart interview questions for 2026. Covers all top categories — Coding & Algorithms, Analytics & Experimentation, Behavioral & Leadership, System Design, and Data Manipulation (SQL/Python) — across Software Engineer, Data Scientist, and Machine Learning Engineer roles. Instacart interview questions in this set come from actual interviews and include detailed solutions, making it a focused resource for interview preparation. What’s distinctive: interviews favor practical, production-minded problems tied to marketplace and fulfillment constraints. Software Engineers see a coding-heavy loop (bus‑boarding simulation metrics, expression evaluation, encoded-string decoding, parser/evaluator tasks, payroll and inventory trackers) plus system-design scenarios about inventory and scaling; Data Scientists get marketplace-metric forensics (D14 retention drops, weekly revenue attribution, Miami Ultrafast effects), experiment design with network effects, and SQL ranking/aggregation; ML Engineers face Core ML reasoning and tight algorithmic tasks. Evaluators look for correctness, trade‑off thinking, metric-driven debugging, and cross‑functional communication. To prepare, practice the specific coding patterns above, sharpen SQL/experiment design, and craft STAR stories that show impact and ownership.

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Compute duration and stopping rules correctly
Experiment Runtime Planning: Same‑Day Delivery Attach Rate You are planning an A/B test on the same‑day delivery attach rate (the proportion of eligib...
Decode a password string into letters
A password is encoded as a string s using the following rules: - Numbers "1" to "9" map to letters a to i. - Numbers "10#" to "26#" (two digits follow...
Evaluate query ratios from equations
You are given equations of the form A / B = value where A and B are variable names (strings) and value is a positive real number. You also receive que...
Solve expression evaluator and string decoder
1) Implement an arithmetic expression evaluator that reads expressions from a text file (one expression per line) and outputs the evaluated result for...
Answer standard behavioral questions
Question Answer the standard behavioral questions asked in an Instacart Software Engineer onsite. Use the STAR framework and make your specific impact...
Investigate marketplace metrics and experiment rollout
You are interviewing for a Senior Data Scientist role at a two-sided marketplace like Instacart, where customers place delivery orders and shoppers ch...
Improve low R² without p‑hacking
Predicting Contribution per Order with Low R² Context You are modeling contribution per order (a continuous per-order outcome such as margin or profit...
Solve a challenge using data
Tell Me About a Time You Solved a High-Stakes Problem With Data You are interviewing for a Data Scientist role and the hiring manager asks you to demo...
Summarize your background concisely
Behavioral Prompt: 60–90 Second Career Walkthrough (Data Scientist, HR Screen) Context You are interviewing for a Data Scientist role in a consumer-te...
Recommend and validate a budget allocation strategy
Using insights you would derive from the SQL task (top advertiser by total spend; most profitable program by net profit and by margin), propose a conc...
Justify Instacart fit and leaving your role
Behavioral HR Screen — Data Scientist Prompt Why Instacart specifically (vs. DoorDash/Uber Eats or your current company)? - Identify 2–3 Instacart pro...
Analyze A/B test with revenue–cost tradeoffs
A/B Test: Same‑Day Delivery Checkout Change You are evaluating a checkout UI change that promotes same‑day delivery. The experiment is a standard two‑...
Design scalable inventory system and avoid races
System Design: Scalable, Highly Available Inventory Management Context Design an inventory management system for a high-traffic e-commerce platform th...
Design an inventory system
Design an Inventory Management System with Real-Time Stock and Ordering Problem You are designing an inventory management service for a retail/marketp...
Diagnose Sunday Miami same‑day outages
Marketplace stability case: same‑day disablement on Sunday afternoons (Miami) Context Instacart offers two fulfillment modes: - Same‑day delivery (rea...
Implement a banking operations system
Implement a simple banking system that manages multiple accounts with initial balances. Support operations: deposit(accountId, amount), withdraw(accou...
Design a scalable inventory system
Design a scalable inventory system System Design: Multi-Warehouse, Multi-Channel Inventory Service You are designing an inventory service for an e-com...
Prioritize conflicting tasks under shifting deadlines
Behavioral: Prioritizing Three Critical Requests Under a One‑Day Constraint Scenario You have 8 hours today and no backup. Three concurrent deliverabl...
Design cloud storage with quotas and compression
System Design: Multi‑Tenant Cloud Storage Service (Take‑Home) You are tasked with designing a multi‑tenant cloud storage service that supports file up...
Implement an In-Memory File Storage System
Implement an in-memory file storage service. You need to support files identified by a unique full path string, such as "/docs/a.txt". Each file has a...