Practice briefStart with your own approach
9. Design Search Autocomplete
Return useful prefix suggestions quickly while refreshing rankings and removing unsafe entries.
ClassicMedium
Guided practice
Start with a template. Work through each step. Ask Coach when you need a second opinion.
All designs 14
Ordered by design numberCompany tags are community-reported. Counts on cards show how many people reported that design.
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- Practice briefStart with your own approach
18. Keep enterprise AI search fresh and private
Handle document changes, ACL revocation and deletion across a retrieval pipeline.
AI systemsHard 48. Design a Ticket Booking System like Ticketmaster
Hold seats with one conditional write, pay by authorize and capture, and put ten million fans in a fair waiting room without selling a seat twice.
ClassicMedium56. Design a Local Business Review Site like Yelp
Search 10 million businesses by place, words and category, keep every average rating exact, and keep fake reviews out.
ClassicMedium57. Design Post Search like Facebook
Search a billion posts a day by keyword, newest or most liked first, with an inverted index you build yourself.
ClassicMedium58. Design a Dating App like Tinder
Stacks of nearby people in under 300 ms, 2 billion swipes a day, and a match never missed even when both like at once.
ClassicMedium71. Design a Search Engine like Elasticsearch
Search a billion documents in 200 ms: inverted indexes, analysers, Lucene segments, shards and replicas, query then fetch with BM25, fed by CDC.
ClassicMedium81. Design a Proximity Search Service
Radius, k-nearest and map-box search over places that rarely move and drivers that ping every few seconds: R-trees, geohash, H3 and S2 cells, Redis GEO and OpenSearch. One-hour boards for junior, senior and staff, with the theory.
ClassicMedium83. Design a Vector Database
Nearest-neighbour search over a billion embeddings: HNSW, IVF-PQ and disk graphs, filters, segments, sharding, and hybrid search with re-ranking.
ClassicMedium95. Design a Team Chat App like Slack
Design a team chat app like Slack: channels and DMs in real time, threads, unread counts and search. One-hour boards for junior, senior and staff, with the theory behind them.
ClassicMedium97. Design a Distributed Logging and Error Tracking System
Ten terabytes of logs an hour from host agents through Kafka into tiered OpenSearch and S3, with regex search, live tail and exceptions grouped into issues.
ClassicMedium99. Design a Cross-Product Tagging System
One set of tags across Jira issues, Confluence pages and Bitbucket pull requests: batch renders, tag pages that never leak, suggestions, popular tags.
ClassicMedium109. Design an Embedding Generation and Indexing Pipeline
Embed a billion chunks on GPUs, keep a k-NN index fresh through CDC with versioned writes and provable deletes, and migrate models blue-green.
ClassicMedium143. Design YouTube Video Search
Find the right videos for a typed query among billions: BM25 and a dual encoder over text, speech and frames, LambdaMART on debiased clicks, human raters.
ClassicMedium