#consistency

18 consistency interview questions, asked at Amazon, Google, Stripe and 8 more companies. Last asked Sep 2026.

Design the metadata service of a strongly consistent distributed file systemSystem designDesign the namespace layer for a distributed file system: make directories, list them, put and get files, delete, and walk the tree recursively. A listing must reflect every write…
Last asked Sep 2026
Design a global caching service for small imagesSystem designDesign a global caching service for small images, backed by a single database that holds every image and is the source of truth. Cover the read path, the update path, the cache…
Last asked Sep 2026
Design a payments ledgerSystem designDesign the double-entry ledger behind a payments API: money movements must never be lost or applied twice.
Last asked Aug 2026
Design an idempotent double-entry ledger serviceSystem designDesign a ledger service that records money movements for merchants as double-entry transactions and answers balance and history queries. Cover the data model, making writes…
Last asked Aug 2026
Order service whose database write succeeds but queue publish failsSystem designDesign the order path of an online bookstore. When an order request arrives, the service inserts the order into its database and then publishes a message to a queue (Amazon SQS)…
Last asked Aug 2026
+1
Design Amazon LockerSystem designLet customers pick a locker location at checkout, assign a compartment that fits the package, and give them a code to collect it within a few days.
Last asked Jul 2026
+3
Design a hotel booking systemSystem designSearch hotels by place and dates, show availability and prices, and book rooms without double-booking, including holds and cancellations.
Last asked Jun 2026
+3
Design a quota serviceSystem designTrack and enforce how much of each resource (API calls, storage, compute) every tenant may use, with fast checks and limits that stay accurate across regions.
Last asked May 2026
Design a superhero dispatch systemSystem designDesign a system that sends superheroes to incidents across a city. An incident is reported with its location; the system finds an available hero nearby, assigns them and tracks…
Last asked May 2026
Design an online shopping cartSystem designKeep a user's cart across devices and sessions, apply prices and promotions correctly, and hand off to checkout reliably.
Last asked May 2026
Design an online auction with live biddingSystem designDesign an auction system where users bid on items (for example items posted on a social app) and everyone watching sees the current highest bid in real time until the auction…
Last asked Feb 2026
Design a globally consistent metadata serviceSystem designDesign a metadata service that stays strongly consistent across regions: every read reflects the latest committed write wherever it is served. Cover the data model, how writes are…
Last asked Jan 2026
+1
Design an access management systemSystem designDecide who can do what to which resource across many services: roles, groups, fine-grained permissions, fast checks on every request, and auditable changes.
Last asked Jan 2026
Design an online auction serviceSystem designDesign an auction feature inside a social app: sellers list an item with an end time, buyers place bids, and everyone watching sees the highest bid update live. Cover the data…
Last asked Oct 2025
Design a migration from a relational database to NoSQLSystem designA live service must move its data from a relational database to a NoSQL store without downtime. Design the migration: modelling the data for the new store, the initial bulk copy…
Last asked Sep 2025
Design a protocol for distributed transactionsSystem designA transaction must update data held by several independent services or shards, so that either all changes happen or none do. Design the protocol: how participants agree to commit…
Last asked Sep 2025
Design a watch history and resume-playback serviceSystem designRecord what each user watched and how far they got, so playback resumes at the right point on any device. Cover the API, how often progress is written, storage for a very large…
Last asked Sep 2025
Versioned key-value vault with consistency checkCodingDesign a versioned key-value vault with filesystem-like structure and a consistency check across versions. Reported on 1point3acres' Harvey bank; reconstructed in our own words.