The design library
Building blocks, complete architectures, and variations worth comparing. Search by the problem you want to solve or a component you want to understand.
Classic designOfficial
Collect from 20,000 publishers by push, polls and crawls, file each article once into feeds by region and category, and serve a billion pages a day from the edge: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Sync files up to 50 GB across devices: presigned multipart uploads, blocks named by hash, a journal per namespace with WebSocket hints, and cold tiers: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Upload tens of gigabytes and stream to any screen: resumable multipart uploads, a chunked transcoding DAG, adaptive bitrate over a CDN: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Photos and videos for 500 million daily users: presigned multipart uploads, a processing pipeline, CloudFront and a hybrid fan-out feed: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
A home feed for 2 billion users: fan-out on read, on write, and the hybrid for huge accounts, with precomputed feeds, cursors and hot posts: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Live prices to five million phones through per-symbol pub/sub, and market and limit orders over FIX that are never lost, sent twice or overspent: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Charge cards through the networks exactly once: idempotency keys, a card vault, timeouts as unknowns, signed webhooks, a double-entry ledger and reconciliation. One-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Show what 10,000 small warehouses can deliver within the hour in under 100 ms, and take multi-item orders without ever selling a unit twice: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Price a trip, match a rider to a nearby driver who has ten seconds to accept, and never give one driver two rides: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Take bids on 10 million live auctions with one consistent highest bid, lose none, push the price to every watcher and end each auction fairly: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
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: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Run strangers' code safely in single-use microVMs, return verdicts within 5 seconds, and rank 100,000 contestants live: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Seven-character codes that never clash, a billion redirects a day from three layers of cache, takedowns everywhere within a minute: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Ten billion pages in five days, politely, without losing progress: fetchers and parsers, domain locks, bandwidth math, deduplication and a crawl that stays fresh. One-hour boards for junior, senior and staff.
Classic designOfficial
Run 10,000 jobs a second within two seconds of their time, at least once, with retries, fairness between tenants and exactly-once effects: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
A terabyte of key-value pairs in memory across fifty nodes, read in a millisecond, with LRU, TTLs, replication, hot keys and stampedes handled: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Allow or reject a million requests a second in under two milliseconds, across every gateway, with limits that hold and rules that change safely: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Watch prices on 500 million products with a polite crawler and a million browsers, verify what you are told, and notify subscribers within minutes of a drop: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
The K most-viewed videos for the last hour, day, month and all time from 700,000 views a second, exactly and in milliseconds: one-hour boards for junior, senior and staff, with the theory behind them.
Classic designOfficial
Collect 5 million samples a second from 500,000 hosts, store them as time series, chart them and page people: one-hour boards for junior, senior and staff, with the theory behind them.
Low-level designOfficial
The classes and code behind the ad click aggregator: signed click tokens, a redirect that never waits on the log, and a stream counter that de-duplicates and handles late clicks. Tests run all of it.
Classic designOfficial
Count every ad click once, fast enough to chart live and exactly enough to bill. One-hour interview boards for junior, senior and staff: requirements, data layer, low-level design and what goes wrong at every component.
Classic designOfficial
Google Calendar-style events with recurrence, RSVPs and on-time reminders, using CDC for change notifications and a delay queue for reminders.
Building blockOfficial
The client uploads to object storage itself with a short-lived signed URL, so large files never pass through the application.