#streaming

44 streaming interview questions, asked at Amazon, Google, OpenAI and 14 more companies. Last asked Oct 2026.

AI-agent security detection over streaming telemetryAI system designDesign a system in which an AI agent reads a stream of security telemetry and runs detections on it. About 1 TB of data arrives per day. It was asked like a traditional system…
Last asked Oct 2026
+5
Design an AI chatbot appAI system designBuild a chatbot app on top of a hosted LLM API: conversations, streamed answers, history, and per-user usage limits.
Last asked Sep 2026
Design durable execution for long-running agent queriesAI system designAn answer service runs each query in memory, but agentic queries can now take hours. Redesign it so a query keeps running and finishes after the browser disconnects, resumes after…
Last asked Sep 2026
Design a real-time 3D playback system for recorded vehicle logsSystem designDesign a system that replays a recorded vehicle drive as an interactive 3D scene. A drive is a set of timestamped logs (sensor data, vehicle pose and similar) kept in object…
Last asked Sep 2026
+1
Oldest one-time visitor in a login streamCodingAn online store wants to know which customers have visited only once. Every login is reported to your service as a username, in the order the logins happen. Implement a class…
Last asked Aug 2026
+7
Design a top-K popular items systemSystem designReport the K most viewed or played items over sliding windows (last minute, hour, day) from a firehose of billions of events per day.
Last asked Aug 2026
Kth largest element in a streamCodingValues arrive one by one. After each value, return the kth largest value seen so far. It was framed as a product catalog that must report its top items.
Last asked Aug 2026
+5
Design an ad click aggregation systemSystem designCount ad clicks per ad and per time window from billions of events a day, accurately enough to bill advertisers, with results available within minutes.
Last asked Aug 2026
Highway toll checkpoints from plate logsCodingA highway has numbered toll checkpoints. Each checkpoint's name contains its position as a number, for example "A1" is at position 1 and "CP12" is at position 12. Ignore every…
Last asked Aug 2026
Design a streaming AI feature for a large audienceAI system designA consumer product wants to add an AI feature whose answers stream to millions of users in real time. Design the path from the client to the model: how responses stream, how…
Last asked Aug 2026
Design log storage with live tailing of growing filesSystem designProducers keep appending records to log files at very high volume. Store them durably and let users read files back, including users who read a file while it is still being…
Last asked Aug 2026
Track missing package IDs from out-of-order arrivalsCodingPackages with IDs 1, 2, 3, ... arrive in any order. Support recording an arrival, reporting the contiguous frontier (the largest ID such that every ID up to it has arrived), and…
Last asked Aug 2026
Design ChatGPT streaming with resumable responses and long conversationsAI system designYou have already sketched a ChatGPT-style chat product. Now go deeper on three follow-ups: how replies stream to the browser (SSE or something else, and why), how a reply survives…
Last asked Jul 2026
Entropy from logits, stable and then streamingCodingCompute the entropy of softmax(logits) for a vector of logits without overflow or underflow. Then the logits come in one by one: keep a fixed amount of state so the exact entropy…
Last asked Jul 2026
Running cost of streamed token usageCodingToken usage for model requests arrives as a stream of usage records rather than all at once. Compute what the usage costs, keeping the totals correct as each new record arrives…
Last asked Jul 2026
Streaming Markdown code parserCodingParse Markdown code fences out of a token stream as it arrives, emitting complete code blocks without waiting for the whole document. Reported on 1point3acres' Cursor bank;…
Last asked Jul 2026
+3
Design SpotifySystem designStream music to hundreds of millions of listeners: catalog, search, playlists, smooth playback over bad networks, and offline downloads.
Last asked May 2026
Design a security monitoring frameworkSystem designDesign a framework that collects security signals such as logs and events from many systems, detects suspicious activity, raises alerts and supports investigations. Cover…
Last asked May 2026
+1
Design a driver location heatmapSystem designShow near-real-time density of available drivers and rider demand on a city map, updated every few seconds from millions of location pings.
Last asked May 2026
Build a chat input that renders a streamed AI replyCodingBuild a minimal ChatGPT-like page: a text box and a submit button, and below them the model's reply, rendered as it streams back from the API rather than all at once. Handle the…
Last asked Apr 2026
Design an embeddable streaming chat interfaceAI system designFor a frontend role: design the interface for a chat agent that other products can embed. Cover the component's API, streaming the agent's replies as they are generated, how…
Last asked Apr 2026
Design a real-time sensor intelligence systemML designDesign a system that takes in sensor data in real time and runs machine learning on it to produce useful signals as the data arrives. Cover ingestion, the models and how they are…
Last asked Apr 2026
Design view counting for product pagesSystem designDesign the backend for product pages on a large shopping site that records how many times each product is viewed. Cover taking in view events at high volume, counting them…
Last asked Apr 2026
Design an ad pacing systemSystem designAdvertisers set a budget for a campaign over a period. Design the system that paces delivery so the budget is spent smoothly over that period instead of running out in the first…
Last asked Apr 2026
Technical recruiter screen: duplicate requests and a streaming chat UISystem designThe first recruiter call is more technical than most. After the background questions (how much of the last year you spent writing code, whether you lean frontend, backend or full…
Last asked Apr 2026
+2
Truncate model output at the first stop sequenceCodingImplement a function that returns the part of a string that comes before the earliest stop word. - text is any string. It may be empty. - stopwords is a list of non-empty strings…
Last asked Mar 2026
+1
Grep with context linesCodingImplement a simplified grep. You get a list of text lines, a search string target, and a non-negative integer k. Return every line that contains target, together with up to k…
Last asked Feb 2026
+1
K-th greatest value in every growing prefixCodingYou are given arr, a permutation of the integers 1 to n (each value appears exactly once), and an integer k with 1 <= k <= n. Read arr from left to right. After reading each…
Last asked Feb 2026
K-th largest value over the last N seconds of a streamCodingStart with finding the k-th largest element of an array. Then values arrive with timestamps and queries ask for the k-th largest among values from the last N seconds; design a…
Last asked Jan 2026
Infrastructure fundamentals: networking, Kubernetes and streamingSystem designA rapid-fire round of around twenty short questions with no coding, for an infrastructure role. Reported ones: 1. What happens between typing a site's address in the browser and…
Last asked Jan 2026
Top-k and bottom-k words in a list and in a streamCoding1. Given a list of words, return the k most frequent and the k least frequent. 2. Now the words arrive as a stream: keep both answers available at any moment. 3. Discuss how to…
Last asked Jan 2026
Classify a stream of tokens with embeddingsML designGiven data that arrives as a stream, process the tokens online, turn them into embeddings, and build a model that classifies them. Cover how you process data as it arrives, which…
Last asked Jan 2026
Design stock price alertsSystem designUsers set alerts such as "tell me when this stock goes above a price". Design the system that watches live prices and notifies the right users quickly. Cover how alert rules are…
Last asked Dec 2025
Design a device telemetry pipeline for real-time and batch useSystem designDevices send telemetry continuously. Design a pipeline that serves real-time monitoring and alerting and also feeds batch analytics: ingestion, buffering, the streaming and batch…
Last asked Dec 2025
Count errors in a log stream with a moving averageSystem designDesign a component that reads a continuous stream of log lines, counts errors per time window and keeps a moving average to spot spikes. Discuss windowing, memory bounds, late or…
Last asked Dec 2025
Running median of a streamCodingNumbers arrive one at a time; after each, report the median of everything seen so far. Use two heaps. Follow-ups: the values come from a small range (use counts instead of heaps);…
Last asked Dec 2025
Maximum value in a file too big for memoryCodingA very large text file holds one number per line. Return the largest value. Then speed it up: split the file into chunks, find each chunk's maximum in parallel, and combine. Write…
Last asked Dec 2025
Reservoir sampling and a check that it is uniformCodingPick k items uniformly at random from a stream of unknown length in one pass and O(k) memory. Then write a simulation that tests whether your picks are close to uniform, and…
Last asked Nov 2025
Stream deduplication with near-duplicate suppressionCodingPass through a stream of strings, keeping only the first copy of each. Then also drop strings that are near-duplicates of something already kept, above a similarity threshold, and…
Last asked Nov 2025
Real-time top-k products from purchase eventsCodingPurchase events (customerid, itemid, timestamp) arrive continuously. Keep a structure that returns the k most purchased items at any moment. Discuss the cost of updates and…
Last asked Sep 2025
Top 10 songs per user from listening historySystem designDesign a system that shows every user of a music service their ten most-played songs, computed from their listening history. Cover ingesting play events, the aggregation (batch…
Last asked Aug 2025
Design batch and streaming ETL pipelinesSystem designA data engineering onsite round on pipelines: design how product events are ingested, cleaned and aggregated into tables that analysts use, first as daily batch jobs and then as…
Last asked Jul 2025
Music player that plays the most frequent unplayed songCodingUsers keep arriving, each with a list of songs, and every song's count goes up each time it appears. The player must always play the most frequent song that has not been played…
Last asked Mar 2025
+3
Design ChatGPTAI system designDesign a consumer chat product backed by a large language model: conversations, streamed replies, history across devices, at 100M weekly users.