--- title: Zanzibar: How Google Answers “Can This User See This... description: Google's Zanzibar is a globally distributed authorization system that answers billions of access control questions per second with strict consistency... canonical: https://daily.dev/posts/zanzibar-how-google-answers-can-this-user-see-this-file-a-few-million-times-a-second-7jya8zw1s twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Zanzibar: How Google Answers “Can This User See This File?” a Few Million Times a Second | daily.dev og:description: Google's Zanzibar is a globally distributed authorization system that answers billions of access control questions per second with strict consistency... og:url: https://daily.dev/posts/zanzibar-how-google-answers-can-this-user-see-this-file-a-few-million-times-a-second-7jya8zw1s og:image: https://api.daily.dev/og/posts/7jYA8ZW1s.png og:image:alt: Zanzibar: How Google Answers “Can This User See This File?” a Few Million Times a Second og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Zanzibar: How Google Answers “Can This User See This File?” a Few Million Times a Second **[Medium](https://daily.dev/sources/medium_js)** · 8 min read · 0 upvotes · 0 comments ## Summary Google's Zanzibar is a globally distributed authorization system that answers billions of access control questions per second with strict consistency guarantees. It models permissions as relation tuples (e.g., 'Emma is a viewer of document:readme'), which form a graph walked at read time rather than materialized flat. To solve the ordering problem — where a revoked permission could still appear valid on a lagging replica — Zanzibar issues consistency tokens called zookies that tie reads to a logical timestamp, built on top of Spanner's TrueTime. Transitive group membership is precomputed by an internal indexing system called Leopard, keeping latency in single-digit milliseconds. The system serves trillions of ACLs at millions of requests per second with 99.999% availability and sub-10ms p95 latency, while unifying authorization logic across all Google products including Drive, Calendar, YouTube, and Cloud. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [How Google Manages Trillions of Authorizations with Zanzibar](https://daily.dev/posts/how-google-manages-trillions-of-authorizations-with-zanzibar-qayr7xrqc) · ByteByteGo · 96 upvotes · 2 comments - [Authorizing 10 Million API Calls Per Second](https://daily.dev/posts/authorizing-10-million-api-calls-per-second-u9c5eng3l) · System Design Codex · 116 upvotes · 1 comments - [Canva Shares S3 Based Architecture for Session Revocation Across Hundreds of Millions of Sessions](https://daily.dev/posts/canva-shares-s3-based-architecture-for-session-revocation-across-hundreds-of-millions-of-sessions-lvycjnjyl) · InfoQ · 1 upvotes · 0 comments - [Permissions belong in the assembly context](https://daily.dev/posts/permissions-belong-in-the-assembly-context-xx6cswsq1) · The New Stack · 0 upvotes · 0 comments - [RAG Permission Testing with Testcontainers & SpiceDB](https://daily.dev/posts/rag-permission-testing-with-testcontainers-spicedb-tb7wo7vjg) · Docker · 1 upvotes · 0 comments --- Tags: [#distributed-systems](https://daily.dev/tags/distributed-systems), [#authorization](https://daily.dev/tags/authorization) [View this post on daily.dev](https://daily.dev/posts/zanzibar-how-google-answers-can-this-user-see-this-file-a-few-million-times-a-second-7jya8zw1s) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Zanzibar: How Google Answers “Can This User See This File?” a Few Million Times a Second","url":"https://daily.dev/posts/zanzibar-how-google-answers-can-this-user-see-this-file-a-few-million-times-a-second-7jya8zw1s","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/zanzibar-how-google-answers-can-this-user-see-this-file-a-few-million-times-a-second-7jya8zw1s"},"datePublished":"2026-07-21T09:49:56.462Z","dateModified":"2026-07-21T09:51:52.174Z","description":"Google's Zanzibar is a globally distributed authorization system that answers billions of access control questions per second with strict consistency...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6376fdd9112384887f60b746d805b933?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6376fdd9112384887f60b746d805b933?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Medium","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Medium","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/medium","url":"https://daily.dev/sources/medium_js"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/zanzibar-how-google-answers-can-this-user-see-this-file-a-few-million-times-a-second-7jya8zw1s","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"distributed-systems,authorization","timeRequired":"PT8M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Medium","item":"https://daily.dev/sources/medium_js"},{"@type":"ListItem","position":3,"name":"Zanzibar: How Google Answers “Can This User See This File?” a Few Million Times a Second"}]} ```