Frontier AI Technical Interview Question Bank

Topic tags
Reliability
Product design

Reported interview periodJan 2026

Design a Shared Calendar Service

Design a calendar system where users create events, invite attendees, view free/busy availability, receive reminders, and edit recurring series across time zones.

Practice focusRequirements - Define APIs and storage for calendars, events, attendees, recurrence rules, exceptions, and reminders. - Represent instants and display time zones correctly across daylight-saving transitions. - Support editing an entire series, one instance, or this-and-future instances. - Resolve concurrent edits and preserve an auditable revision history. - Compute free/busy efficiently for users with many calendars and access restrictions. - Deliver reminders reliably without sending duplicates.…

Free practice

Topic tags
Reliability

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodJan 2026

Design a URL Shortening Service

Design a service that creates durable short links and resolves them with low latency under a read-heavy workload.

Practice focusRequirements - Define create, resolve, custom-alias, delete, and analytics APIs. - Generate compact identifiers with low collision risk and no single hot coordinator at target scale. - Preserve custom-alias uniqueness under concurrent requests. - Support expiry, abuse prevention, and safe-link checks. - Cache popular redirects without serving deleted or changed mappings indefinitely. - State traffic, data-retention, latency, and availability assumptions.…

Free practice

Topic tags
Networking
Reliability
Product design

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodNov 2025

Design a reliable webhook delivery platform

Design a multi-tenant service that delivers customer events to externally managed HTTP endpoints. Customer endpoints may be slow, unavailable for hours, or return ambiguous failures. The platform must protect i…

Practice focusScenario Design a multi-tenant service that delivers customer events to externally managed HTTP endpoints. Customer endpoints may be slow, unavailable for hours, or return ambiguous failures. The platform must protect its own availability while giving customers secure, observable, and replayable delivery. Assume high sustained event volume, bursty tenants, multiple endpoints per tenant, and payloads that must be delivered in order for some event streams. Functional requirements - Register, verify, rotate secrets for, pause, and delete webhook endpoints.…

Free practice

Topic tags
Reliability
Product design

OpenAISystem designHalf AI-generated

Discussion / designResponse prompt

Reported interview periodNot available

Tool execution platform

Design a platform where an AI assistant invokes approved tools on behalf of users. Include tool registration, argument validation, identity and consent, isolated execution, timeouts, idempotency, audit logs, an…

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
Concurrency
Reliability
Product design

OpenAISystem designAI-generated

Discussion / designResponse prompt

Reported interview periodApr 2026–Sep 2026

Design a Long-Running Video Generation Platform

Design a service where users submit prompts for video generation. Jobs consume scarce accelerators, may run for minutes, can be cancelled, and must survive worker failure.

Practice focusRequirements - Define APIs for submit, status, progress streaming, cancel, retry, and result retrieval. - Queue and schedule jobs under per-user quotas, priorities, and accelerator constraints. - Use leases or heartbeats so abandoned work becomes recoverable. - Make retries safe, preserve checkpoints, and avoid publishing partial or duplicate results. - Store inputs and outputs securely with retention and content-safety controls. - Provide honest progress despite phases with uncertain duration.…

Public brief

Topic tags
Python
Data structures
Concurrency
Storage & state
Reliability

OpenAICodingHalf AI-generated

Python codingWebAssembly + public tests

Reported interview periodAug 2026–Sep 2026

Leased Work Queue with Dead-Letter Handling

Implement an in-memory queue whose jobs are reserved with expiring leases. A failed worker must not hold a job forever, and jobs that exceed their retry budget move to a dead-letter state.

Practice focusRequirements and assumptions - Jobs move among ready , reserved , completed , and dead . - reserve increments attempts and returns {item id, token} plus an internal deadline. - On explicit failure or lease deadline <= now , return the job to ready unless attempts reached max attempts ; then mark it dead. - Completion or failure with a stale token returns False without changing state. - Queue ready jobs deterministically and reject duplicate active IDs. - Validate positive limits and use the explicit clock supplied by callers. Follow-ups 1.…

Public brief

Topic tags
Python
Storage & state
Reliability

OpenAICoding

Python codingWebAssembly + public tests2 versions

Reported interview periodNov 2025–Aug 2026

Persist a string map across restart

Implement a durable string-to-string key-value store using the provided FileSystem abstraction.

Practice focusIn the base task, shutdown() commits a complete snapshot using FileSystem.save blob(bytes) . A newly constructed store starts empty; restore() recovers the latest saved snapshot. The supplied storage replaces a whole blob atomically and remains alive across store instances. It models snapshot persistence, not partial writes or a real disk. Keys and values may contain arbitrary Unicode characters, including newlines; use a length-prefixed binary format rather than delimiter-only encoding. Do not use JSON or pickle.…

Public brief

Topic tags
Python
Algorithms
Data structures
Storage & state
Networking

Coding exerciseCodingAI-generated

Runnable 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
Data structures
Reliability
Data / SQL

Coding exerciseCodingAI-generated

Runnable coding50 min

Reported interview periodN/A

Dependency-ready scheduler

Turn a dependency graph into stable ready sets, execution layers, and failure impact.

Practice focusPython, Graphs, Stable ordering, Cycle detection, Failure analysis through a runnable coding exercise.

Public brief

Topic tags
Data structures
Concurrency
Storage & state
Reliability
ML / AI

System designSystem designAI-generated

Written response75–100 min

Reported interview periodN/A

Build a reliable job runner

Review staged prompts that begin with a small in-memory worker, then introduce retries, duplication, cancellation, and process restarts.

Practice focusState modeling, Idempotency, Retry policy, Failure recovery, Operational reasoning through a written response exercise.

Public brief

Topic tags
Reliability
Communication

Project deep diveProject deep diveAI-generated

Written response60–90 min

Reported interview periodN/A

Prepare one project deep dive

Build a defensible walkthrough of a project from problem framing to architecture, experiments, failures, and outcomes.

Practice focusArchitecture, Experiment design, Debugging, Metrics, Trade-offs through a written response exercise.

Public brief

Topic tags
Reliability
ML / AI
Data / SQL

System designSystem designAI-generated

Written response70–90 min

Reported interview periodN/A

Design an evaluation artifact registry

Design a reproducible registry connecting datasets, evaluator configurations, model outputs, and reviewed results.

Practice focusData lineage, Versioning, Idempotency, Access control, Reproducibility through a written response exercise.

Public brief

Topic tags
Reliability
Communication

Project deep diveProject deep diveAI-generated

Written response60–85 min

Reported interview periodN/A

Trace a project from claim to evidence

Prepare a technical project account that connects the initial claim, experiment design, implementation choices, failures, and shipped evidence.

Practice focusProblem framing, Experiment design, Architecture, Debugging, Evidence quality through a written response exercise.

Public brief

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

OpenAISystem designAI-generated

Written 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

Written 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
Communication
Reliability

Project deep diveProject deep dive

Written response25 minutes

Reported interview periodN/A

After launch

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

Practice focusA shipped system, Measurement through a written response exercise.

Frontier AI technical interview question bank.

Frontier AI technical interview question bank.

Design a Shared Calendar Service

Design a URL Shortening Service

Design a reliable webhook delivery platform

Tool execution platform

Design a Long-Running Video Generation Platform

Leased Work Queue with Dead-Letter Handling

Persist a string map across restart

Sliding-window rate limiter

Dependency-ready scheduler

Build a reliable job runner

Prepare one project deep dive

Design an evaluation artifact registry

Trace a project from claim to evidence

A mutable indexed sequence that must restart exactly

Shared scratch pad

After launch

Design a Shared Calendar Service

Design a URL Shortening Service

Design a reliable webhook delivery platform

Tool execution platform

Design a Long-Running Video Generation Platform

Leased Work Queue with Dead-Letter Handling

Persist a string map across restart

Sliding-window rate limiter

Dependency-ready scheduler

Build a reliable job runner

Prepare one project deep dive

Design an evaluation artifact registry

Trace a project from claim to evidence

A mutable indexed sequence that must restart exactly

Shared scratch pad

After launch