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Question bank

Frontier AI technical interview question bank.

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

Company

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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 43 Coding 23 System design 13 Behavioral 3 Hiring manager 2 Project deep dive 2

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.

38 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.

Public brief

Topic tags
Python
Storage & state

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJul 2025–May 2026

Implement a Quota-Aware Cloud File Store

Process a sequence of string commands against a flat cloud-storage namespace. Every command returns one result string.

Practice focusOperations - Add a file with a unique name and integer size; copy an existing file to a free name; query a file's size. - Find files matching both a prefix and suffix, sorted by size descending and then name ascending. - Add quota-limited users and add user-owned files only when capacity permits. - Reduce a user's capacity, evicting that user's largest files first and using name order to break ties until usage fits. - Compress an owned file by renaming it with a .COMPRESSED suffix and halving its even size.…

Public brief

Topic tags
Python
Storage & state
Networking

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a DNS Resolver with Aliases and TTL

Build an in-memory resolver over A and CNAME records.

Practice focusRequirements - Normalize domain names case-insensitively and ignore a trailing dot. - An A record resolves directly to its address while live. - A CNAME follows its target recursively until a live A record is found. - Each record has type ( A or CNAME ) and value (address or target). Optional ttl is a duration; set at defaults to zero. A missing or null ttl means no expiration. - A record expires when now = set at + ttl . - Any expired or missing link makes resolution fail.…

Public brief

Topic tags
Python
Storage & state
Communication

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a Task Manager with Expiration and Historical Views

Tasks are scoped by (user, task_id). Implement creation, mutation, TTL expiration, and snapshots.

Practice focusRequirements - A task key can be created only once, even if the task later completes or expires. - Only live incomplete tasks can be updated or completed. - TTL is anchored at creation; a task is absent at and after created at + ttl , and updates do not refresh it. - Current lists contain live incomplete titles ordered by task ID. - A historical list includes all events at or before the requested timestamp and applies expiration relative to that historical time. - Calls arrive in nondecreasing command time, though historical query times may be earlier.…

New public brief

Topic tags
Python
Storage & state

xAICoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Apr 2026

In-Memory Database with Expiry and Snapshots

Build an in-memory database in four stages. Each key owns string field/value pairs.

Practice focusMissing values return "" . Scans emit field(value) entries sorted by field. A TTL value is live over [created at, created at + ttl) . A backup captures all live fields and each field's remaining lifetime. Restore selects the newest backup at or before timestamp to restore , replaces current state, and restarts remaining lifetimes at timestamp . Assume timestamps supplied to mutating timed operations are nondecreasing. Backups must not share mutable state with the live database.…

New public brief

Topic tags
Python
Data structures
Storage & state
Networking

xAICoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026

Token-Bucket State Transitions

Each subject has a token bucket stored in a shared key-value cache. A missing bucket begins full. Refill lazily when a request arrives: add elapsed_time * refill_rate, capped at capacity. If time has not advanc…

Practice focusAccept only when the refilled balance covers the full request, then subtract it. A rejected request spends nothing. Persist the refilled state in either case. A backward-moving clock must not create tokens. TokenBucket and the in-memory DistributedCache test double are provided. This base task is sequential; the cache name does not imply atomic distributed behavior. Refill returns a new bucket without editing its argument. Existing buckets retain their stored capacity/refill rate; call configuration initializes missing buckets only.…

New public brief

Topic tags
Python
Storage & state

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Course Schedule

There are num_courses courses labeled 0 through num_courses - 1. Each prerequisite pair (course, prerequisite) states that the prerequisite must be completed first.

Practice focusImplement: Return whether it is possible to complete every course. Courses with no edges are valid, and duplicate prerequisite pairs should not change the answer. Aim for O(V + E) time. Staged follow-ups 1. Return one valid course order, or an empty list when none exists. 2. Return an explicit cycle to explain why the schedule is impossible. 3. Process prerequisite additions incrementally and reject an addition that creates a cycle.

Public brief

Topic tags
Storage & state

xAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

A board of ten scores

Ten people store one score per run and look at which run is ahead this week.

Practice focusSystem design round. Ten people record one score per run. Say what a week means and what a missing score shows. Walk the write and the read. A score arrives twice for the same run. Keep the first. Stop when the board can say this week is still open.

Public brief

Topic tags
Storage & state
Communication

xAIBehavioralHalf AI-generated

Discussion / designResponse prompt

Reported interview periodNot available

Fast feedback and correction

Tell one story where you shipped a bounded first version, learned that an assumption was wrong, and corrected it quickly. State the boundary, signal, correction, and impact without hiding the original mistake.

Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…

Public brief

Topic tags
Python
Algorithms
Data structures
Storage & state
Networking

Coding exerciseCodingAI-generated

Practice formatRunnable coding45 min

Reported interview periodN/A

Sliding-window rate limiter

Build a limiter, then add quota reporting, retry timing, and independent keys.

Practice focusPython, Queues, State, Boundary cases, Complexity through a runnable coding exercise.

Public brief

Topic tags
Python
Storage & state

Coding exerciseCodingAI-generated

Practice formatRunnable coding45 min

Reported interview periodN/A

Command-log store

Evolve a tiny state machine through undo, compaction, and snapshot replay.

Practice focusPython, State machines, Undo logs, Compaction, Persistence through a runnable coding exercise.

Public brief

Topic tags
Python
Data structures
Storage & state

Coding exerciseCodingAI-generated

Practice formatRunnable coding50 min

Reported interview periodN/A

Streaming metric window

Compute ordered rolling metrics, then partition state and expose freshness explicitly.

Practice focusPython, Queues, Streaming state, Boundaries, Observability through a runnable coding exercise.

Public brief

Topic tags
Algorithms
Data structures
Storage & state
Reliability
Data / SQL

OpenAISystem designAI-generated

Practice formatWritten response45–60 min

Reported interview periodN/A

A mutable indexed sequence that must restart exactly

Design a sequence that stays fast to index, accepts mutation, and can crash at any point without losing the state a reader already saw. Then make the restart path provable rather than plausible.

Practice focusData structure design, Complexity analysis, Durability, Crash recovery through a written response exercise.

Public brief

Topic tags
Storage & state
Reliability

System designSystem design

Practice formatWritten response45 minutes

Reported interview periodN/A

Shared scratch pad

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

Practice focusConflict, Failure through a written response exercise.

Public brief

Topic tags
Storage & state
Data / SQL

System designSystem design

Practice formatWritten response45 minutes

Reported interview periodN/A

Weekly score board

Store a score per model run and show which run is ahead this week.

Practice focusRead path, Write path through a written response exercise.

Previous2 of 2Next

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 43 Coding 23 System design 13 Behavioral 3 Hiring manager 2 Project deep dive 2

Topics

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

38 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.

Public brief

Topic tags
Python
Storage & state

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodJul 2025–May 2026

Implement a Quota-Aware Cloud File Store

Process a sequence of string commands against a flat cloud-storage namespace. Every command returns one result string.

Public brief

Topic tags
Python
Storage & state
Networking

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a DNS Resolver with Aliases and TTL

Build an in-memory resolver over A and CNAME records.

Public brief

Topic tags
Python
Storage & state
Communication

AnthropicCoding

Python codingWebAssembly + public tests

Reported interview periodMay 2026

Implement a Task Manager with Expiration and Historical Views

Tasks are scoped by (user, task_id). Implement creation, mutation, TTL expiration, and snapshots.

New public brief

Topic tags
Python
Storage & state

xAICoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Apr 2026

In-Memory Database with Expiry and Snapshots

Build an in-memory database in four stages. Each key owns string field/value pairs.

New public brief

Topic tags
Python
Data structures
Storage & state
Networking

xAICoding

Python codingWebAssembly + public tests

Reported interview periodApr 2026

Token-Bucket State Transitions

New public brief

Topic tags
Python
Storage & state

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Course Schedule

There are num_courses courses labeled 0 through num_courses - 1. Each prerequisite pair (course, prerequisite) states that the prerequisite must be completed first.

Public brief

Topic tags
Storage & state

xAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodNot available

A board of ten scores

Ten people store one score per run and look at which run is ahead this week.

Public brief

Topic tags
Storage & state
Communication

xAIBehavioralHalf AI-generated

Discussion / designResponse prompt

Reported interview periodNot available

Fast feedback and correction

Public brief

Topic tags
Python
Algorithms
Data structures
Storage & state
Networking

Coding exerciseCodingAI-generated

Practice formatRunnable coding45 min

Reported interview periodN/A

Sliding-window rate limiter

Build a limiter, then add quota reporting, retry timing, and independent keys.

Practice focusPython, Queues, State, Boundary cases, Complexity through a runnable coding exercise.

Public brief

Topic tags
Python
Storage & state

Coding exerciseCodingAI-generated

Practice formatRunnable coding45 min

Reported interview periodN/A

Command-log store

Evolve a tiny state machine through undo, compaction, and snapshot replay.

Practice focusPython, State machines, Undo logs, Compaction, Persistence through a runnable coding exercise.

Public brief

Topic tags
Python
Data structures
Storage & state

Coding exerciseCodingAI-generated

Practice formatRunnable coding50 min

Reported interview periodN/A

Streaming metric window

Compute ordered rolling metrics, then partition state and expose freshness explicitly.

Practice focusPython, Queues, Streaming state, Boundaries, Observability through a runnable coding exercise.

Public brief

Topic tags
Algorithms
Data structures
Storage & state
Reliability
Data / SQL

OpenAISystem designAI-generated

Practice formatWritten response45–60 min

Reported interview periodN/A

A mutable indexed sequence that must restart exactly

Design a sequence that stays fast to index, accepts mutation, and can crash at any point without losing the state a reader already saw. Then make the restart path provable rather than plausible.

Practice focusData structure design, Complexity analysis, Durability, Crash recovery through a written response exercise.

Public brief

Topic tags
Storage & state
Reliability

System designSystem design

Practice formatWritten response45 minutes

Reported interview periodN/A

Shared scratch pad

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

Practice focusConflict, Failure through a written response exercise.

Public brief

Topic tags
Storage & state
Data / SQL

System designSystem design

Practice formatWritten response45 minutes

Reported interview periodN/A

Weekly score board

Store a score per model run and show which run is ahead this week.

Practice focusRead path, Write path through a written response exercise.

Previous2 of 2Next

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