[{"data":1,"prerenderedAt":529},["ShallowReactive",2],{"guide-unique-identifiers-guide":3},{"id":4,"title":5,"body":6,"date":519,"description":520,"extension":521,"meta":522,"navigation":523,"path":524,"readingTime":525,"seo":526,"stem":527,"__hash__":528},"guides\u002Fguides\u002Funique-identifiers-guide.md","Unique Identifiers in Software: A Practical Guide",{"type":7,"value":8,"toc":506},"minimark",[9,14,18,22,25,31,44,49,60,63,67,70,81,85,96,100,111,120,124,127,133,137,148,152,160,168,172,175,181,185,196,200,211,214,218,221,227,231,245,249,260,263,267,434,438,472,476,494,498],[10,11,13],"h2",{"id":12},"why-unique-identifiers-matter","Why Unique Identifiers Matter",[15,16,17],"p",{},"Every software system needs a way to uniquely identify records — users, orders, messages, files. The identifier strategy you choose impacts database performance, distributed coordination, security, and API design. This guide compares five common approaches so you can pick the right one.",[10,19,21],{"id":20},"auto-increment-integers","Auto-Increment Integers",[15,23,24],{},"The simplest approach: the database assigns each row the next sequential integer (1, 2, 3…).",[15,26,27],{},[28,29,30],"strong",{},"Strengths:",[32,33,34,38,41],"ul",{},[35,36,37],"li",{},"Compact storage (4 or 8 bytes)",[35,39,40],{},"Naturally sorted — excellent for clustered indexes",[35,42,43],{},"Easy to read and reference in URLs",[15,45,46],{},[28,47,48],{},"Weaknesses:",[32,50,51,54,57],{},[35,52,53],{},"Single point of coordination — hard to generate across distributed nodes",[35,55,56],{},"Predictable — attackers can enumerate records",[35,58,59],{},"Migration between databases requires remapping IDs",[15,61,62],{},"Use auto-increment for small, single-database applications where simplicity outweighs scalability.",[10,64,66],{"id":65},"uuid-128-bit","UUID (128-bit)",[15,68,69],{},"UUIDs provide 128-bit identifiers generated without central coordination. Version 4 (random) is the most common.",[71,72,77],"pre",{"className":73,"code":75,"language":76},[74],"language-text","550e8400-e29b-41d4-a716-446655440000\n","text",[78,79,75],"code",{"__ignoreMap":80},"",[15,82,83],{},[28,84,30],{},[32,86,87,90,93],{},[35,88,89],{},"No coordination needed — any node can generate independently",[35,91,92],{},"Negligible collision probability",[35,94,95],{},"Supports merging datasets without ID conflicts",[15,97,98],{},[28,99,48],{},[32,101,102,105,108],{},[35,103,104],{},"128 bits = 36 characters as text, 16 bytes as binary",[35,106,107],{},"UUID v4 is random — causes index fragmentation in databases",[35,109,110],{},"Not human-readable",[15,112,113,114,119],{},"Use UUID when systems must generate IDs independently, like microservices or offline-first apps. If database performance matters, prefer ",[115,116,118],"a",{"href":117},"\u002Fguides\u002Fuuid-versions-explained","UUID v7"," over v4.",[10,121,123],{"id":122},"ulid-128-bit-sortable","ULID (128-bit, Sortable)",[15,125,126],{},"ULID (Universally Unique Lexicographically Sortable Identifier) combines a 48-bit timestamp with 80 bits of randomness, encoded as 26-character Crockford's Base32 strings.",[71,128,131],{"className":129,"code":130,"language":76},[74],"01ARZ3NDEKTSV4RRFFQ69G5FAV\n",[78,132,130],{"__ignoreMap":80},[15,134,135],{},[28,136,30],{},[32,138,139,142,145],{},[35,140,141],{},"Sortable by generation time — database-friendly",[35,143,144],{},"URL-safe encoding (no special characters)",[35,146,147],{},"Compatible with UUID's 128-bit space",[15,149,150],{},[28,151,48],{},[32,153,154,157],{},[35,155,156],{},"Less widely supported than UUID in libraries and databases",[35,158,159],{},"Millisecond precision — sub-millisecond ordering is not guaranteed",[15,161,162,163,167],{},"Use ULID when you need sortability and compact representation. See our ",[115,164,166],{"href":165},"\u002Fguides\u002Fuuid-vs-ulid","UUID vs ULID comparison"," for a deeper dive.",[10,169,171],{"id":170},"snowflake-ids-64-bit","Snowflake IDs (64-bit)",[15,173,174],{},"Popularized by Twitter, Snowflake IDs combine a timestamp, datacenter ID, worker ID, and sequence number into a 64-bit integer.",[71,176,179],{"className":177,"code":178,"language":76},[74],"1541815603606036480\n",[78,180,178],{"__ignoreMap":80},[15,182,183],{},[28,184,30],{},[32,186,187,190,193],{},[35,188,189],{},"Compact — fits in a 64-bit integer",[35,191,192],{},"Time-ordered and sortable",[35,194,195],{},"Highly efficient for database indexing",[15,197,198],{},[28,199,48],{},[32,201,202,205,208],{},[35,203,204],{},"Requires coordinator to assign worker\u002Fdatacenter IDs",[35,206,207],{},"Depends on system clock — clock skew causes issues",[35,209,210],{},"64-bit limits total identifiers (roughly 69 years of IDs per worker)",[15,212,213],{},"Use Snowflake when you operate at scale with many nodes writing to the same database and need compact, sortable IDs.",[10,215,217],{"id":216},"nanoid-21-character","NanoID (21-character)",[15,219,220],{},"NanoID generates compact, URL-safe strings using a larger alphabet than UUID, achieving similar uniqueness in fewer characters.",[71,222,225],{"className":223,"code":224,"language":76},[74],"V1StGXR8_Z5jdHi6B-myT\n",[78,226,224],{"__ignoreMap":80},[15,228,229],{},[28,230,30],{},[32,232,233,236,239,242],{},[35,234,235],{},"21 characters vs UUID's 36 — shorter URLs",[35,237,238],{},"URL-safe by default",[35,240,241],{},"Extremely fast generation",[35,243,244],{},"Zero dependencies",[15,246,247],{},[28,248,48],{},[32,250,251,254,257],{},[35,252,253],{},"Not standardized — different alphabets change the output",[35,255,256],{},"Not time-sortable",[35,258,259],{},"Shorter length means slightly higher collision probability (still negligible for most apps)",[15,261,262],{},"Use NanoID for URL-friendly identifiers like short links, file names, or component keys in front-end code.",[10,264,266],{"id":265},"comparison-table","Comparison Table",[268,269,270,295],"table",{},[271,272,273],"thead",{},[274,275,276,280,283,286,289,292],"tr",{},[277,278,279],"th",{},"Property",[277,281,282],{},"Auto-Increment",[277,284,285],{},"UUID",[277,287,288],{},"ULID",[277,290,291],{},"Snowflake",[277,293,294],{},"NanoID",[296,297,298,321,341,359,378,395,414],"tbody",{},[274,299,300,306,309,312,315,318],{},[301,302,303],"td",{},[28,304,305],{},"Length",[301,307,308],{},"4–8 bytes",[301,310,311],{},"36 chars",[301,313,314],{},"26 chars",[301,316,317],{},"8 bytes",[301,319,320],{},"21 chars",[274,322,323,328,331,334,336,338],{},[301,324,325],{},[28,326,327],{},"Sortable",[301,329,330],{},"Yes",[301,332,333],{},"v4: No \u002F v7: Yes",[301,335,330],{},[301,337,330],{},[301,339,340],{},"No",[274,342,343,348,350,352,354,357],{},[301,344,345],{},[28,346,347],{},"Distributed",[301,349,340],{},[301,351,330],{},[301,353,330],{},[301,355,356],{},"Partial",[301,358,330],{},[274,360,361,366,369,372,374,376],{},[301,362,363],{},[28,364,365],{},"Collision risk",[301,367,368],{},"None",[301,370,371],{},"Negligible",[301,373,371],{},[301,375,368],{},[301,377,371],{},[274,379,380,385,387,389,391,393],{},[301,381,382],{},[28,383,384],{},"URL-safe",[301,386,330],{},[301,388,330],{},[301,390,330],{},[301,392,330],{},[301,394,330],{},[274,396,397,402,405,407,409,412],{},[301,398,399],{},[28,400,401],{},"Coordination",[301,403,404],{},"Database",[301,406,368],{},[301,408,368],{},[301,410,411],{},"Worker ID assignment",[301,413,368],{},[274,415,416,421,424,427,429,432],{},[301,417,418],{},[28,419,420],{},"Best scale",[301,422,423],{},"Small",[301,425,426],{},"Any",[301,428,426],{},[301,430,431],{},"Large-scale",[301,433,426],{},[10,435,437],{"id":436},"when-to-use-which","When to Use Which",[32,439,440,446,452,457,462,467],{},[35,441,442,445],{},[28,443,444],{},"Auto-increment",": Single-server apps, internal tools, prototyping",[35,447,448,451],{},[28,449,450],{},"UUID v4",": Microservices, systems with no central DB, offline-first",[35,453,454,456],{},[28,455,118],{},": Same as v4 but with database sortability",[35,458,459,461],{},[28,460,288],{},": When you want sortable + compact + URL-safe",[35,463,464,466],{},[28,465,291],{},": High-throughput distributed systems (thousands of writes\u002Fsec)",[35,468,469,471],{},[28,470,294],{},": Client-side keys, short URLs, file naming",[10,473,475],{"id":474},"related-guides","Related Guides",[32,477,478,483,488],{},[35,479,480],{},[115,481,482],{"href":117},"UUID Versions Explained",[35,484,485],{},[115,486,487],{"href":165},"UUID vs ULID",[35,489,490],{},[115,491,493],{"href":492},"\u002Fguides\u002Fpassword-security","Password Security",[10,495,497],{"id":496},"try-it-yourself","Try It Yourself",[15,499,500,501,505],{},"Generate UUIDs in multiple versions instantly with our free ",[115,502,504],{"href":503},"\u002Ftools\u002Fuuid-generator","UUID Generator",". Test sortability, compare formats, and copy results — no signup needed.",{"title":80,"searchDepth":507,"depth":507,"links":508},2,[509,510,511,512,513,514,515,516,517,518],{"id":12,"depth":507,"text":13},{"id":20,"depth":507,"text":21},{"id":65,"depth":507,"text":66},{"id":122,"depth":507,"text":123},{"id":170,"depth":507,"text":171},{"id":216,"depth":507,"text":217},{"id":265,"depth":507,"text":266},{"id":436,"depth":507,"text":437},{"id":474,"depth":507,"text":475},{"id":496,"depth":507,"text":497},"2026-05-27","Learn about different unique identifier strategies. Compare auto-increment, UUID, ULID, Snowflake IDs, and NanoID for your projects.","md",{"immutable":523},true,"\u002Fguides\u002Funique-identifiers-guide",6,{"title":5,"description":520},"guides\u002Funique-identifiers-guide","Qx3uio7lxDsxYbmrB4M-TgUtXbI6MDQkAVlxkDZ9CFM",1780401325612]