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.

"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"

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"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."

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"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."

"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."

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"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."

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"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."

"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."

"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."

"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Design an e-commerce category page
Design an e-commerce category page System Design: Category Page with Facets, Sorting, Pagination, SEO, Caching, Personalization, and Real-Time Updates...
Decode an encoded string
Implement a decoder for an encoded string where repetition is expressed with a number followed by a bracketed substring. Rules: - A pattern k[substrin...
Design a versioned key-value store
Design a versioned key-value store Design and implement a versioned key-value store that supports set(key, value, timestamp) and get(key, timestamp) t...
Discuss conflict, failure, and leadership examples
Discuss conflict, failure, and leadership examples Behavioral & Leadership (Software Engineer Onsite) Prepare four STAR stories that demonstrate your ...
Diagnose 4% weekly revenue drop using history
You only have a single table weekly_revenue(week_start_date DATE, revenue_usd NUMERIC) containing the last 104 weeks for Instacart. A DS reports that ...
Optimize file reading and expression DFS
Optimize file reading and expression DFS Given a large password file, build a program to read the required password(s) while minimizing memory usage. ...
Evaluate arithmetic expression with precedence
Question Implement an evaluator for a string arithmetic expression. The input contains non-negative integers, the operators +, -, `, /, parentheses ( ...
Evaluate arithmetic expression using DFS
Given a string representing an arithmetic expression with non-negative integers, +, -, *, /, parentheses, and optional spaces, evaluate its value. Use...
Optimize file reads for password validation
Given a multi-gigabyte credentials file on disk with one record per line in the format user_id,salt,password_hash (hex), implement validate(user_id, p...
Compute delivery wait times
You're building a last‑mile delivery simulator. Given n orders, each with arrival_time (non-decreasing integers) and service_time (positive integers),...
Diagnose and fix low conversion rigorously
Diagnose a Checkout Conversion Drop After a Promo Banner Launch Scenario Week-over-week, checkout conversion fell from 42% to 35% after a new promo ba...
Describe challenges and proud accomplishment
Describe challenges and proud accomplishment Behavioral: Significant Challenge and Proud Accomplishment (Software Engineer Onsite) Provide two concise...
Parse password from indexed matrix file
Question Given a filepath to a text file containing one index line [x, y] followed by a matrix of characters (origin at lower-left (0, 0)), return the...
Parse a password from a matrix
Given an m x n matrix of characters, a starting coordinate (row, col), and a string of moves consisting of 'U', 'D', 'L', 'R', parse a password by vis...
Pivot data without date libraries
Transform a tall dataset into a wide, pivoted view without using any date/time libraries. Input: a list of records (date, store_id, metric, value) whe...
Compute and optimize average wait time
You are given n pickup orders for a grocery delivery counter. Each order i is described by orders[i] = [arrival_i, service_i] in minutes, where arriva...
Implement matrix-indexing and expression resolver
Question Given a text file path whose contents include a single block starting with a line like "[2,4]" followed by rows of equal-length characters (e...
Write SQL to rank advertisers and profitability
You are given two denormalized tables. Use ANSI SQL (CTEs allowed) and UNPIVOT (or an equivalent UNION ALL approach if UNPIVOT is unavailable). Table:...
Aggregate weekly revenue and attribute 4% drop
Write SQL over the following schema to: (A) compute weekly revenue by ISO week (Monday–Sunday) from orders, excluding cancelled/refunded; revenue_usd ...
Compute average customer waiting time
Compute average customer waiting time You are given n customer orders; each order i = [a_i, p_i] where a_i is the arrival time and p_i is the preparat...