[{"data":1,"prerenderedAt":436},["ShallowReactive",2],{"blog-post-what-is-uuid-and-how-to-generate":3},{"id":4,"title":5,"author":6,"body":7,"description":421,"draft":422,"extension":423,"lang":424,"meta":425,"navigation":330,"path":426,"pubDate":427,"relatedTool":428,"seo":429,"stem":430,"tags":431,"__hash__":435},"blog\u002Fblog\u002Fwhat-is-uuid-and-how-to-generate.mdx","What Is a UUID and How to Generate One Online","ujiffy team",{"type":8,"value":9,"toc":409},"minimark",[10,19,24,39,42,53,57,60,146,151,158,162,168,172,175,179,182,188,194,200,206,212,216,219,241,248,252,255,281,284,287,387,390,394,397,405],[11,12,13,14,18],"p",{},"If you've spent any time working with databases, APIs, or distributed systems, you've almost certainly encountered UUIDs. They look like this: ",[15,16,17],"code",{},"550e8400-e29b-41d4-a716-446655440000",". Seemingly random, oddly specific in format, and absolutely everywhere. But what exactly are they, why are they useful, and which version should you use? Let's break it down.",[20,21,23],"h2",{"id":22},"what-is-a-uuid","What Is a UUID?",[11,25,26,30,31,34,35,38],{},[27,28,29],"strong",{},"UUID"," stands for ",[27,32,33],{},"Universally Unique Identifier",". It's a 128-bit label used to uniquely identify information in computer systems. The format is always the same: 32 hexadecimal characters split into five groups by hyphens — ",[15,36,37],{},"8-4-4-4-12",".",[11,40,41],{},"The \"universally unique\" part is the key selling point. UUIDs are designed so that any two independently generated UUIDs will almost certainly be different — even if generated on different machines at the same time, without any coordination between them. This makes them extremely useful in distributed systems where you can't rely on a central authority to assign sequential IDs.",[11,43,44,45,52],{},"UUIDs are standardized by ",[46,47,51],"a",{"href":48,"rel":49},"https:\u002F\u002Fwww.rfc-editor.org\u002Frfc\u002Frfc4122",[50],"nofollow","RFC 4122"," and are widely supported across virtually every programming language and database system.",[20,54,56],{"id":55},"uuid-versions-explained","UUID Versions Explained",[11,58,59],{},"There are several UUID versions, each generated differently and suited to different use cases. The three most commonly used are v1, v4, and v5.",[61,62,63,85],"table",{},[64,65,66],"thead",{},[67,68,69,73,76,79,82],"tr",{},[70,71,72],"th",{},"Version",[70,74,75],{},"Generation Method",[70,77,78],{},"Uniqueness Source",[70,80,81],{},"Predictable?",[70,83,84],{},"Common Use Case",[86,87,88,108,127],"tbody",{},[67,89,90,96,99,102,105],{},[91,92,93],"td",{},[27,94,95],{},"v1",[91,97,98],{},"Timestamp + MAC address",[91,100,101],{},"Time + hardware",[91,103,104],{},"Partially",[91,106,107],{},"Event logging, audit trails",[67,109,110,115,118,121,124],{},[91,111,112],{},[27,113,114],{},"v4",[91,116,117],{},"Random",[91,119,120],{},"Pure randomness",[91,122,123],{},"No",[91,125,126],{},"General purpose, databases",[67,128,129,134,137,140,143],{},[91,130,131],{},[27,132,133],{},"v5",[91,135,136],{},"Namespace + name (SHA-1)",[91,138,139],{},"Deterministic",[91,141,142],{},"Yes (same input → same UUID)",[91,144,145],{},"Consistent IDs for known resources",[147,148,150],"h3",{"id":149},"uuid-v1-timestamp-based","UUID v1 — Timestamp-Based",[11,152,153,154,157],{},"v1 UUIDs encode the current timestamp and the MAC address of the machine generating them. They're time-ordered, which can be useful for sorting. However, they ",[27,155,156],{},"leak information"," — if you inspect a v1 UUID, you can extract when and where (roughly) it was created. For privacy-sensitive applications, this is a concern.",[147,159,161],{"id":160},"uuid-v4-random","UUID v4 — Random",[11,163,164,165],{},"v4 is the most widely used version today. It's generated from 122 bits of randomness (the other 6 bits encode the version and variant). There's no timestamp, no machine info — just random data. The probability of two v4 UUIDs colliding is so astronomically low it's effectively impossible in practice. ",[27,166,167],{},"When in doubt, use v4.",[147,169,171],{"id":170},"uuid-v5-name-based-sha-1","UUID v5 — Name-Based (SHA-1)",[11,173,174],{},"v5 generates a UUID from a namespace UUID and a name string, using SHA-1 hashing. The same namespace + name always produces the same UUID. This is useful when you want a consistent, reproducible identifier for a known resource — for example, always generating the same UUID for a given URL or user email. Note: v3 does the same thing but with MD5 (less preferred today).",[20,176,178],{"id":177},"common-use-cases-for-uuids","Common Use Cases for UUIDs",[11,180,181],{},"UUIDs are versatile. Here's where developers reach for them most often:",[11,183,184,187],{},[27,185,186],{},"Database primary keys","\nInstead of auto-incrementing integers, many applications use UUID primary keys. The advantage: records can be created across multiple servers or clients without ID collisions, and the IDs don't expose how many records exist in your database.",[11,189,190,193],{},[27,191,192],{},"File naming and storage","\nWhen uploading user files to object storage (S3, R2, etc.), using a UUID as the filename prevents conflicts and avoids exposing the original filename to the storage layer.",[11,195,196,199],{},[27,197,198],{},"Session IDs and tokens","\nUUIDs make great session identifiers — long enough to be unguessable, short enough to be practical. Most web frameworks will generate UUID-based session tokens out of the box.",[11,201,202,205],{},[27,203,204],{},"Distributed event tracking","\nIn event-driven or microservice architectures, UUIDs are used as correlation IDs to trace a request across multiple services in logs and monitoring systems.",[11,207,208,211],{},[27,209,210],{},"Client-side ID generation","\nIn offline-first apps or mobile clients, records can be created on the device with a UUID before syncing to the server. No round-trip to the server needed just to get an ID.",[20,213,215],{"id":214},"uuid-v4-vs-v1-vs-v5-which-should-you-use","UUID v4 vs v1 vs v5 — Which Should You Use?",[11,217,218],{},"The short answer for most use cases:",[220,221,222,229,235],"ul",{},[223,224,225,228],"li",{},[27,226,227],{},"Use v4"," if you just need a unique, opaque ID and don't need it to be reproducible.",[223,230,231,234],{},[27,232,233],{},"Use v1"," if you need time-sortable IDs and privacy is not a concern.",[223,236,237,240],{},[27,238,239],{},"Use v5"," if you need to derive a consistent ID from a known name or resource.",[11,242,243,244,247],{},"For new projects, ",[27,245,246],{},"v4 is the safe default"," unless you have a specific reason to choose otherwise.",[20,249,251],{"id":250},"how-to-generate-a-uuid-online","How to Generate a UUID Online",[11,253,254],{},"If you need a UUID for testing, development, or configuration, you don't need to write any code. ujiffy's free UUID generator lets you:",[220,256,257,264,271,274],{},[223,258,259,260,263],{},"Generate ",[27,261,262],{},"one or multiple UUIDs"," at once",[223,265,266,267,270],{},"Choose between ",[27,268,269],{},"v1, v4, and v5"," versions",[223,272,273],{},"Copy results to clipboard instantly",[223,275,276,277,280],{},"Everything runs ",[27,278,279],{},"in your browser"," — no server involved",[11,282,283],{},"No sign-up, no rate limits, no tracking.",[11,285,286],{},"For developers who need UUIDs in code, here are quick snippets:",[288,289,294],"pre",{"className":290,"code":291,"language":292,"meta":293,"style":293},"language-js shiki shiki-themes material-theme-lighter material-theme material-theme-palenight","\u002F\u002F JavaScript (browser or Node 14.17+)\ncrypto.randomUUID() \u002F\u002F generates a v4 UUID\n\n\u002F\u002F Python\nimport uuid\nstr(uuid.uuid4())\n\n\u002F\u002F Go\nimport \"github.com\u002Fgoogle\u002Fuuid\"\nuuid.New().String()\n","js","",[15,295,296,305,325,332,338,348,354,359,365,381],{"__ignoreMap":293},[297,298,301],"span",{"class":299,"line":300},"line",1,[297,302,304],{"class":303},"sHwdD","\u002F\u002F JavaScript (browser or Node 14.17+)\n",[297,306,308,312,315,319,322],{"class":299,"line":307},2,[297,309,311],{"class":310},"sTEyZ","crypto",[297,313,38],{"class":314},"sMK4o",[297,316,318],{"class":317},"s2Zo4","randomUUID",[297,320,321],{"class":310},"() ",[297,323,324],{"class":303},"\u002F\u002F generates a v4 UUID\n",[297,326,328],{"class":299,"line":327},3,[297,329,331],{"emptyLinePlaceholder":330},true,"\n",[297,333,335],{"class":299,"line":334},4,[297,336,337],{"class":303},"\u002F\u002F Python\n",[297,339,341,345],{"class":299,"line":340},5,[297,342,344],{"class":343},"s7zQu","import",[297,346,347],{"class":310}," uuid\n",[297,349,351],{"class":299,"line":350},6,[297,352,353],{"class":310},"str(uuid.uuid4())\n",[297,355,357],{"class":299,"line":356},7,[297,358,331],{"emptyLinePlaceholder":330},[297,360,362],{"class":299,"line":361},8,[297,363,364],{"class":303},"\u002F\u002F Go\n",[297,366,368,371,374,378],{"class":299,"line":367},9,[297,369,370],{"class":310},"import ",[297,372,373],{"class":314},"\"",[297,375,377],{"class":376},"sfazB","github.com\u002Fgoogle\u002Fuuid",[297,379,380],{"class":314},"\"\n",[297,382,384],{"class":299,"line":383},10,[297,385,386],{"class":310},"uuid.New().String()\n",[11,388,389],{},"But if you just need one right now — the generator is faster.",[20,391,393],{"id":392},"final-thoughts","Final Thoughts",[11,395,396],{},"UUIDs are a simple but powerful primitive in software development. They solve the \"how do I generate a unique ID without coordination?\" problem elegantly. For most applications, v4 is all you need. If you're building something more specific — time-ordered logs, or deterministic IDs for known resources — v1 or v5 have you covered.",[11,398,399],{},[46,400,402],{"href":401},"\u002Ftools\u002Fuuid-generator",[27,403,404],{},"Try ujiffy UUID Generator →",[406,407,408],"style",{},"html pre.shiki code .sHwdD, html code.shiki .sHwdD{--shiki-light:#90A4AE;--shiki-light-font-style:italic;--shiki-default:#546E7A;--shiki-default-font-style:italic;--shiki-dark:#676E95;--shiki-dark-font-style:italic}html pre.shiki code .sTEyZ, html code.shiki .sTEyZ{--shiki-light:#90A4AE;--shiki-default:#EEFFFF;--shiki-dark:#BABED8}html pre.shiki code .sMK4o, html code.shiki .sMK4o{--shiki-light:#39ADB5;--shiki-default:#89DDFF;--shiki-dark:#89DDFF}html pre.shiki code .s2Zo4, html code.shiki .s2Zo4{--shiki-light:#6182B8;--shiki-default:#82AAFF;--shiki-dark:#82AAFF}html pre.shiki code .s7zQu, html code.shiki .s7zQu{--shiki-light:#39ADB5;--shiki-light-font-style:italic;--shiki-default:#89DDFF;--shiki-default-font-style:italic;--shiki-dark:#89DDFF;--shiki-dark-font-style:italic}html pre.shiki code .sfazB, html code.shiki .sfazB{--shiki-light:#91B859;--shiki-default:#C3E88D;--shiki-dark:#C3E88D}html .light .shiki span {color: var(--shiki-light);background: var(--shiki-light-bg);font-style: var(--shiki-light-font-style);font-weight: var(--shiki-light-font-weight);text-decoration: var(--shiki-light-text-decoration);}html.light .shiki span {color: var(--shiki-light);background: var(--shiki-light-bg);font-style: var(--shiki-light-font-style);font-weight: var(--shiki-light-font-weight);text-decoration: var(--shiki-light-text-decoration);}html .default .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html.dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}",{"title":293,"searchDepth":307,"depth":307,"links":410},[411,412,417,418,419,420],{"id":22,"depth":307,"text":23},{"id":55,"depth":307,"text":56,"children":413},[414,415,416],{"id":149,"depth":327,"text":150},{"id":160,"depth":327,"text":161},{"id":170,"depth":327,"text":171},{"id":177,"depth":307,"text":178},{"id":214,"depth":307,"text":215},{"id":250,"depth":307,"text":251},{"id":392,"depth":307,"text":393},"Understand what UUIDs are, the difference between UUID v1, v4, and v5, and how to generate collision-free unique IDs instantly — free and browser-based.",false,"mdx","en",{},"\u002Fblog\u002Fwhat-is-uuid-and-how-to-generate","2025-05-15","uuid-generator",{"title":5,"description":421},"blog\u002Fwhat-is-uuid-and-how-to-generate",[29,432,433,434],"unique ID","developer tools","uuid generator","S70h0Ur16PQ4zvFE1LH945b3RVOj4oaHT8LSvSnVS-o",1778831414325]