UUID Generator
Generate unique identifiers for documents, records, or workflows.
UUID Generator — what it does
Generate universally unique identifiers, one at a time or ten at once, using the browser's cryptographic random source. A UUID is a 128-bit value formatted as 36 characters, and the point of it is that two systems can each create one without coordinating and still never collide.
When this tool helps
- Creating primary keys for records that must be unique across several systems or databases.
- Generating correlation identifiers to trace a request through a distributed system.
- Producing unique filenames or reference codes without a central counter.
How to use it
- Generate a single UUID, or ten at once.
- Read the generated values.
- Copy the one you need.
- Generate again for more.
Accuracy, limits, and good practice
- Random UUIDs carry no ordering, so using them as a clustered database key can hurt insert performance — sequential variants exist for that reason.
- They are unique, not secret: a UUID in a URL is guessable in the sense that it identifies a resource, so do not use one as an access token.
- Store them as a native UUID type where your database offers one; as text they take 36 bytes instead of 16.
Frequently asked questions
Can two UUIDs collide?
The probability is negligible. You would need to generate billions per second for decades before a collision became likely.
What is the difference between UUID versions?
Version 4 is random, version 1 embeds a timestamp and MAC address, and newer time-ordered versions improve database locality.
Is a UUID safe to expose in a URL?
It identifies rather than authorises. Exposing one is fine as long as access control does not depend on the identifier being unknown.
Related tools on this site
- Interleave Two PDFs — Alternate pages from two PDF files into one document
- Insert PDF Separator Pages — Insert labeled separator pages at a chosen interval
- Word Counter — Count words and characters instantly
Everything above runs inside this page. UUID Generator needs no account, no upload, and no server round trip — close the tab and nothing is left behind.
UUID 產生器能做什麼
以瀏覽器的密碼學隨機來源產生通用唯一識別碼，可一次產生一個或十個。UUID 是格式化為 36 個字元的 128 位元值，它的重點在於：兩個系統各自產生，卻仍然不會撞在一起。
什麼時候用得上
- 為必須跨多個系統或資料庫保持唯一的紀錄建立主鍵。
- 產生關聯識別碼，用來追蹤請求在分散式系統中的流向。
- 在沒有中央計數器的情況下產生唯一檔名或參考代碼。
使用步驟
- 產生單一 UUID，或一次產生十個。
- 查看產生的數值。
- 複製需要的那一個。
- 需要更多就再產生一次。
精確度、限制與實務建議
- 隨機 UUID 不帶順序，拿來當叢集索引鍵可能拖慢寫入效能——正是為此才有時間排序的變體。
- 它是唯一而非機密：網址中的 UUID 只是識別資源，不該當成存取權杖使用。
- 資料庫若有原生 UUID 型別就用它；存成文字要 36 位元組，原生型別只需 16。
常見問題
兩個 UUID 會撞號嗎？
機率微乎其微。要每秒產生數十億個、持續數十年，撞號才會變得有可能。
各版本 UUID 差在哪？
第 4 版是隨機的，第 1 版內嵌時間戳與 MAC 位址，較新的時間排序版本則改善了資料庫的局部性。
UUID 可以放在網址中嗎？
它是識別而非授權。只要存取控制不依賴「別人猜不到」，公開它就沒問題。
本站相關工具
- 雙 PDF 交錯合併 — 將兩個 PDF 的頁面輪流合併為一個檔案
- 插入 PDF 分隔頁 — 依指定間隔插入帶標籤的分隔頁
- 字數統計 — 快速統計字數與字元數
以上步驟全部在這個頁面內完成，UUID 產生器 不需要註冊、不上傳檔案、也不經過伺服器，關閉分頁後不會留下任何資料。