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Question bank

Frontier AI technical interview question bank.

Practice coding, system design, behavioral, and project questions for frontier AI roles.

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Frontier Rehearsal · Independent practice · Not affiliated with OpenAI, Anthropic, or xAI.

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Home
Question bank

Frontier AI technical interview question bank.

Practice coding, system design, behavioral, and project questions for frontier AI roles.

Company

FREE PRACTICE

Public demos, always pinned.

Start with either demo. They remain here when you filter or sort.

Free account: sign in to practice the marked Free questions.

Newest published questions; deterministic, never randomized.

Demo 1Number search with delayed feedback
Demo 2Design real-time device monitoring and control

Question bank filters

Reset filters

Question groups

Filter question bank by interview groupAll 269 Coding 162 System design 48 Behavioral 29 Hiring manager 16 Project deep dive 14

Topics

Filter question bank by topic tagsAll 269 Python 161 Algorithms 40 Data structures 46 Concurrency 27 Distributed systems 7 Storage & state 43 Networking 7 Reliability 30 ML / AI 27 Data / SQL 24 Security 7 Product design 25 Communication 66

Independent and not affiliated with the companies represented. Collected material does not predict future interview questions.

213 questions

Sort question bankSortFree first Newest Oldest AI ratio ↓AI ratio ↑

Question bank results

Every question has a public brief with the task, constraints, and follow-ups. Labels describe interactive practice access.

Free practice

Topic tags
Python
Storage & state
Data / SQL

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025

In-Memory Relational Tables and Queries

Implement a small in-memory database supporting table creation, row insertion, filtering, projection, and ordering.

Practice focusRequirements - Reject duplicate tables and rows containing unknown columns; define defaults for missing columns. - where , when supplied, is a predicate over a row. - Projection returns only requested existing columns and must not expose mutable internal rows. - order by=(columns, ascending) sorts lexicographically by listed columns with deterministic ties. - Define null and mixed-type comparison behavior. - Preserve insertion order when no ordering is requested. Follow-ups 1. Add joins and grouped aggregations. 2.…

Free practice

Topic tags
Python
Concurrency
Product design

DatabricksCoding

Talk-through codingNo local grader

Reported interview periodOct 2025

Thread-Safe Channel Chat

Implement an in-memory chat service in which users subscribe to channels, messages are appended to channel histories, and users read messages from their current subscriptions.

Practice focusRequirements - Methods may run concurrently and shared state must be protected explicitly. - Sending appends [channel id, user id, message] even if the sender is not subscribed. - Reading concatenates histories for the user's current subscriptions in sorted channel-id order; each channel remains in send order. - Unsubscribing hides that channel's history from subsequent reads. - Repeated subscribe or unsubscribe operations should be idempotent. - Define the consistency point of each operation and avoid exposing partially written messages.…

Free practice

Topic tags
Python
Storage & state

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025

Implement a time-indexed key-value store

Build an in-memory key-value store that keeps historical values. A caller may ask for the value of a key as of a particular timestamp.

Practice focusScenario Build an in-memory key-value store that keeps historical values. A caller may ask for the value of a key as of a particular timestamp. Interface Requirements - set records a version of key at timestamp . - Timestamps for a key may arrive out of order. - get(key, timestamp) returns the value associated with the greatest stored timestamp less than or equal to the requested time. - Return "" when the key has no qualifying version. - If the same key and timestamp are written more than once, the most recent call replaces the earlier value.…

Free practice

Topic tags
Data / SQL

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodOct 2025

Design a nearby-places search service

Design a consumer service that returns nearby businesses with ratings, opening hours, and recent reviews. A user supplies a location, an optional query or category, and filters such as “open now.” Results shoul…

Practice focusScenario Design a consumer service that returns nearby businesses with ratings, opening hours, and recent reviews. A user supplies a location, an optional query or category, and filters such as “open now.” Results should feel fresh and should rank useful places ahead of merely close places. Assume a metropolitan launch with tens of millions of businesses globally, high read traffic, and continuous updates from business owners and reviewers. Core requirements - Search by latitude/longitude and radius, optionally constrained by text or category.…

Free practice

Topic tags
Python
Algorithms
Concurrency

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Clockwise Spiral Matrix

Return all values of an m × n matrix in clockwise spiral order, beginning at the top-left corner.

Practice focusUse O(1) auxiliary space excluding the returned list, and do not mutate the matrix. Handle empty, single-row, single-column, square, and rectangular matrices. Staged follow-ups 1. Generate an n × n matrix filled from 1 through n² in spiral order. 2. Expose a lazy iterator rather than building the result. 3. Traverse counterclockwise or from an arbitrary corner without duplicating the entire algorithm.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Longest Substring Without Repeated Characters

Given a string, return the length of its longest contiguous substring containing no repeated character.

Practice focusThe empty string returns 0 . Treat characters as the language runtime's Unicode characters. Target O(n) time and O(k) space, where k is the number of distinct characters in the active input. Staged follow-ups 1. Return the substring or its half-open index range, not just its length. 2. Permit each character to appear at most m times. 3. Process a stream in chunks without retaining the entire prefix.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Merge Closed Intervals

Given a list of closed intervals [start, end], merge every overlapping pair and return the resulting non-overlapping intervals sorted by start position.

Practice focusAssume start <= end . Because intervals are closed, [1, 4] and [4, 6] overlap and become [1, 6] . The input may be unsorted and may contain duplicates. Staged follow-ups 1. Preserve associated metadata while merging. 2. Insert one interval into an already sorted, disjoint sequence. 3. Process intervals that arrive as a stream and discuss when output can be finalized.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Minimum Interval Removals

Given intervals [start, end], remove as few as possible so that the remaining intervals do not overlap. Intervals that only touch at an endpoint are compatible.

Practice focusAssume every interval satisfies start <= end . The input may be unsorted and may contain duplicates. Target O(n log n) time. Staged follow-ups 1. Return the retained or removed interval indices. 2. Assign positive weights and maximize retained weight rather than retained count. 3. Handle online arrivals and explain which guarantees can no longer be optimal.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Number of Islands

Given a rectangular grid of characters, where '1' is land and '0' is water, return the number of edge-connected land components. Diagonal cells are not connected.

Practice focusThe grid may be empty. You may either mutate the grid or maintain separate visited state, but state your choice. Target O(rows columns) time. Staged follow-ups 1. Return the area of the largest island. 2. Count islands as land cells are added incrementally. 3. Process a grid too large to hold fully in memory, one row at a time.

Free practice

Topic tags
Python
Data structures

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Reverse a Singly Linked List

Given the head of a singly linked list, reverse its links in place and return the new head.

Practice focusDo not allocate a second list. An empty list and a one-node list should be returned unchanged. The iterative solution should use O(1) auxiliary space. Staged follow-ups 1. Provide a recursive implementation and compare its space usage. 2. Reverse only the nodes between positions left and right . 3. Reverse nodes in fixed-size groups while leaving a final short group unchanged.

Free practice

Topic tags
Python

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Valid Bracket Sequence

Given a string containing only (, ), [, ], {, and }, determine whether every opener is closed by the matching type in the correct order.

Practice focusThe empty string is valid. A closing bracket with no pending opener is invalid, as is any opener left at the end. Target O(n) time and O(n) worst-case space. Staged follow-ups 1. Ignore brackets inside quoted strings while respecting escape characters. 2. Report the location and expected token for the first mismatch. 3. Validate a stream incrementally across chunk boundaries.

Free practice

Topic tags
Python
Data / SQL

xAICoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Earliest Completion Time in a Data Pipeline

A pipeline consists of tasks (inputs, output, duration). A dataset never produced by any task is a source available at time 0. A task may start as soon as every input is available, and independent tasks run in …

Practice focusImplement: Return the earliest time at which goal is available. A goal that is already a source returns 0 . Reject negative durations, duplicate output producers, dependency cycles, and unknown goals with ValueError . Durations are non-negative non-boolean integers; dataset names are strings. A known source is a dataset mentioned as an input but never produced; an arbitrary unmentioned name is unknown. Validate the complete pipeline, including cycles disconnected from the goal. Duplicate input names do not require multiple executions.…

Free practice

Topic tags
Python

xAICoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Fixed-Window Token Limiter

Implement a per-key limiter with one shared token limit and fixed window length. Commands are:

Practice focus- ("ALLOW", key, cost, timestamp) : accept if the key's usage plus cost does not exceed the limit; a rejected request consumes nothing. - ("RESET", key, timestamp) : clear that key's usage in the fixed window containing timestamp . The window containing time t starts at (t // window) window . Costs are non-negative integers; zero is allowed. Preserve input order. Return one result per command, using booleans for ALLOW and a consistent acknowledgment for RESET .…

Free practice

Topic tags
Storage & state

AnthropicSystem designAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

A note two people share

Two people edit one note and both need to see the last line that was saved.

Practice focusSystem design round. Two people share one note. Say where the note is stored. Say what both people see when they save the same line. Say what the second person sees when their save does not land. Stop when a third person can only read.

Free practice

Topic tags
Communication

AnthropicHiring managerAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

The team you would join

A hiring-manager conversation about one team and one project you already owned.

Practice focusHiring-manager round. Stay on one project you owned. Name the team and the problem they had. Say what you decided and who else had to agree. Give one measurement from the month after. The interviewer asks what you would stop if that team were half its size. Name the stop, and the sentence you would use to tell them. Do not switch projects.

Free practice

Topic tags
Communication

xAIHiring managerAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

The run you would own

A hiring-manager conversation about one run you owned and what you would keep if the team shrank.

Practice focusHiring-manager round. Stay on one run you owned. Name what the run was for and what broke. Say what you kept and what you stopped. Give one measurement from the week after. The interviewer asks who you told first and what you promised not to claim. Do not switch runs.

Free practice

Topic tags
Communication

AnthropicHiring manager

Discussion / designResponse prompt

Reported interview periodNot available

Half the team

What you would cut if the team lost half its people.

Practice focusHiring-manager round. Half the team is gone next month. Stay on one project. First, list the work you stop and the work you keep, with the reason for each. Then the interviewer asks who you tell first and what you say in the first minute. Include the sentence, and include one promise you will not make. Then they ask what you would measure two weeks later to know the cut was the right one. Answer with one measurement.

Free practice

Topic tags
Communication

OpenAIHiring manager

Discussion / designResponse prompt

Reported interview periodNot available

Half the team

What you would cut if the team lost half its people.

Free practice

Topic tags
Communication

xAIHiring manager

Discussion / designResponse prompt

Reported interview periodNot available

Half the team

What you would cut if the team lost half its people.

Free practice

Topic tags
Storage & state

AnthropicSystem design

Discussion / designResponse prompt

Reported interview periodNot available

Shared scratch pad

Two people edit one note and need to see who wrote the last line.

Practice focusSystem design round. Two people share one scratch pad during a review. Start by listing what must be true: neither person loses a line, and both can point at who wrote the last line. Place the note in one store and give each save a version. Walk the case where both save the same version. Then the network drops the second save: the first person must not think the second line landed. Then add a third reader who only watches. Say what that reader sees, what you store, and what you would not build for a note this small.

Free practice

Topic tags
Storage & state

OpenAISystem design

Discussion / designResponse prompt

Reported interview periodNot available

Shared scratch pad

Two people edit one note and need to see who wrote the last line.

Free practice

Topic tags
Storage & state

xAISystem design

Discussion / designResponse prompt

Reported interview periodNot available

Shared scratch pad

Two people edit one note and need to see who wrote the last line.

Free practice

Topic tags
Communication

AnthropicProject deep dive

Discussion / designResponse prompt

Reported interview periodNot available

After launch

Where a design failed after launch, what you measured, and what you changed.

Practice focusProject round. One system, after launch. Start with the design you intended. Then the failure, including who felt it. Then the measurement, including the unit and the window. Then the change. The interviewer asks what you left alone and why. Answer with one thing you refused to change. Then they ask how you would know the failure had returned. Point at the same measurement. Do not switch projects.

Free practice

Topic tags
Communication

OpenAIProject deep dive

Discussion / designResponse prompt

Reported interview periodNot available

After launch

Where a design failed after launch, what you measured, and what you changed.

Previous2 of 9Next

Browse all original practice

Build a token-budget batcher
Sliding-window rate limiter
Interval calendar
Nested dictionary transforms
Command-log store
Dependency-ready scheduler
Streaming metric window
Evaluation slice aggregator
Build a reliable job runner
Build one adaptable decision story
Defend your role fit
Prepare one project deep dive
Design an evaluation artifact registry
Defend a reversible launch decision
Negotiate an ambiguous role scope
Trace a project from claim to evidence
Choose between two urgent priorities
Resolve a cross-functional disagreement
Own a consequential failure
Increase a team’s leverage
Warm a cold cache without a thundering herd
Ship a 500 GB checkpoint without a startup stampede
Make every document decision traceable to evidence
Share eight GPUs between two workloads with different promises
A mutable indexed sequence that must restart exactly
Trace a falling unit price to a rising bill
Keep a very long conversation usable while it streams
Design durable scheduled publishing
Make speculative code edits safe to accept
Recover a grouping rule from two-word phrases

CONTENT BOUNDARY

Independent frontier AI interview practice. Includes adaptations of collected interview material and original exercises; not official company questions and not affiliated with the companies represented. Collected material does not predict future interview questions. Report a correction.

Loading the question catalog…

FREE PRACTICE

Public demos, always pinned.

Start with either demo. They remain here when you filter or sort.

Free account: sign in to practice the marked Free questions.

Newest published questions; deterministic, never randomized.

Demo 1Number search with delayed feedback
Demo 2Design real-time device monitoring and control

Question bank filters

Reset filters

Question groups

Filter question bank by interview groupAll 269 Coding 162 System design 48 Behavioral 29 Hiring manager 16 Project deep dive 14

Topics

Independent and not affiliated with the companies represented. Collected material does not predict future interview questions.

213 questions

Sort question bankSortFree first Newest Oldest AI ratio ↓AI ratio ↑

Question bank results

Every question has a public brief with the task, constraints, and follow-ups. Labels describe interactive practice access.

Free practice

Topic tags
Python
Storage & state
Data / SQL

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025

In-Memory Relational Tables and Queries

Implement a small in-memory database supporting table creation, row insertion, filtering, projection, and ordering.

Free practice

Topic tags
Python
Concurrency
Product design

DatabricksCoding

Talk-through codingNo local grader

Reported interview periodOct 2025

Thread-Safe Channel Chat

Implement an in-memory chat service in which users subscribe to channels, messages are appended to channel histories, and users read messages from their current subscriptions.

Free practice

Topic tags
Python
Storage & state

OpenAICoding

Python codingWebAssembly + public tests

Reported interview periodOct 2025

Implement a time-indexed key-value store

Build an in-memory key-value store that keeps historical values. A caller may ask for the value of a key as of a particular timestamp.

Free practice

Topic tags
Data / SQL

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodOct 2025

Design a nearby-places search service

Free practice

Topic tags
Python
Algorithms
Concurrency

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Clockwise Spiral Matrix

Return all values of an m × n matrix in clockwise spiral order, beginning at the top-left corner.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Longest Substring Without Repeated Characters

Given a string, return the length of its longest contiguous substring containing no repeated character.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Merge Closed Intervals

Given a list of closed intervals [start, end], merge every overlapping pair and return the resulting non-overlapping intervals sorted by start position.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Minimum Interval Removals

Given intervals [start, end], remove as few as possible so that the remaining intervals do not overlap. Intervals that only touch at an endpoint are compatible.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Number of Islands

Given a rectangular grid of characters, where '1' is land and '0' is water, return the number of edge-connected land components. Diagonal cells are not connected.

Free practice

Topic tags
Python
Data structures

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Reverse a Singly Linked List

Given the head of a singly linked list, reverse its links in place and return the new head.

Free practice

Topic tags
Python

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Valid Bracket Sequence

Given a string containing only (, ), [, ], {, and }, determine whether every opener is closed by the matching type in the correct order.

Free practice

Topic tags
Python
Data / SQL

xAICoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Earliest Completion Time in a Data Pipeline

Free practice

Topic tags
Python

xAICoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Fixed-Window Token Limiter

Implement a per-key limiter with one shared token limit and fixed window length. Commands are:

Free practice

Topic tags
Storage & state

AnthropicSystem designAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

A note two people share

Two people edit one note and both need to see the last line that was saved.

Free practice

Topic tags
Communication

AnthropicHiring managerAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

The team you would join

A hiring-manager conversation about one team and one project you already owned.

Free practice

Topic tags
Communication

xAIHiring managerAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

The run you would own

A hiring-manager conversation about one run you owned and what you would keep if the team shrank.

Free practice

Topic tags
Communication

AnthropicHiring manager

Discussion / designResponse prompt

Reported interview periodNot available

Half the team

What you would cut if the team lost half its people.

Free practice

Topic tags
Communication

OpenAIHiring manager

Discussion / designResponse prompt

Reported interview periodNot available

Half the team

What you would cut if the team lost half its people.

Free practice

Topic tags
Communication

xAIHiring manager

Discussion / designResponse prompt

Reported interview periodNot available

Half the team

What you would cut if the team lost half its people.

Free practice

Topic tags
Storage & state

AnthropicSystem design

Discussion / designResponse prompt

Reported interview periodNot available

Shared scratch pad

Two people edit one note and need to see who wrote the last line.

Free practice

Topic tags
Storage & state

OpenAISystem design

Discussion / designResponse prompt

Reported interview periodNot available

Shared scratch pad

Two people edit one note and need to see who wrote the last line.

Free practice

Topic tags
Storage & state

xAISystem design

Discussion / designResponse prompt

Reported interview periodNot available

Shared scratch pad

Two people edit one note and need to see who wrote the last line.

Free practice

Topic tags
Communication

AnthropicProject deep dive

Discussion / designResponse prompt

Reported interview periodNot available

After launch

Where a design failed after launch, what you measured, and what you changed.

Free practice

Topic tags
Communication

OpenAIProject deep dive

Discussion / designResponse prompt

Reported interview periodNot available

After launch

Where a design failed after launch, what you measured, and what you changed.

Previous2 of 9Next

Browse all original practice

Build a token-budget batcher
Sliding-window rate limiter
Interval calendar
Nested dictionary transforms
Command-log store
Dependency-ready scheduler
Streaming metric window
Evaluation slice aggregator
Build a reliable job runner
Build one adaptable decision story
Defend your role fit
Prepare one project deep dive
Design an evaluation artifact registry
Defend a reversible launch decision
Negotiate an ambiguous role scope
Trace a project from claim to evidence
Choose between two urgent priorities
Resolve a cross-functional disagreement
Own a consequential failure
Increase a team’s leverage
Warm a cold cache without a thundering herd
Ship a 500 GB checkpoint without a startup stampede
Make every document decision traceable to evidence
Share eight GPUs between two workloads with different promises
A mutable indexed sequence that must restart exactly
Trace a falling unit price to a rising bill
Keep a very long conversation usable while it streams
Design durable scheduled publishing
Make speculative code edits safe to accept
Recover a grouping rule from two-word phrases

CONTENT BOUNDARY