UUID GENERATOR

Standalone, zero-dependency JavaScript implementation powering this tool. Free to inspect, copy, and build upon.

function uuidv4() {
    if (crypto.randomUUID) return crypto.randomUUID();
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
      const r = crypto.getRandomValues(new Uint8Array(1))[0] % 16;
      return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
    });
  }

  function uuidv7() {
    const ms = BigInt(Date.now());
    const rand = new Uint8Array(10);
    crypto.getRandomValues(rand);
    const hi = ms >> 12n;
    const lo = ms & 0xfffn;
    const b = new Uint8Array(16);
    // Bytes 0-5: 48-bit timestamp
    b[0] = Number((hi >> 8n) & 0xffn);
    b[1] = Number(hi & 0xffn);
    b[2] = Number((ms >> 24n) & 0xffn);
    b[3] = Number((ms >> 16n) & 0xffn);
    b[4] = Number((ms >> 8n) & 0xffn);
    b[5] = Number(ms & 0xffn);
    // Byte 6: version (7)
    b[6] = 0x70 | (rand[0] & 0x0f);
    b[7] = rand[1];
    // Byte 8: variant (10xx)
    b[8] = 0x80 | (rand[2] & 0x3f);
    for (let i = 9; i < 16; i++) b[i] = rand[i - 7];
    const hex = Array.from(b).map(x => x.toString(16).padStart(2,'0')).join('');
    return `${hex.slice(0,8)}-${hex.slice(8,12)}-${hex.slice(12,16)}-${hex.slice(16,20)}-${hex.slice(20)}`;
  }

  function applyFormat(uuid) {
    const fmt = document.getElementById('format').value;
    if (fmt === 'upper') return uuid.toUpperCase();
    if (fmt === 'nohyphen') return uuid.replace(/-/g, '');
    if (fmt === 'urn') return 'urn:uuid:' + uuid;
    return uuid;
  }

  const INFO = {
    v4: 'UUID v4 is generated using <strong>cryptographically secure random numbers</strong>. Each UUID is completely random and has no structure encoding time or location.',
    v7: 'UUID v7 uses a <strong>Unix millisecond timestamp</strong> in the most significant bits, making them sortable by creation time. Ideal for database primary keys.',
  };

  function updateInfo() {
    document.getElementById('versionInfo').innerHTML = INFO[document.getElementById('version').value];
  }

  let lastUUIDs = [];

  function generate() {
    const ver = document.getElementById('version').value;
    const count = parseInt(document.getElementById('count').value);
    lastUUIDs = Array.from({ length: count }, () => ver === 'v7' ? uuidv7() : uuidv4());
    const html = lastUUIDs.map((uuid, i) => {
      const display = applyFormat(uuid);
      return `<div class="uuid-item">
        <div class="uuid-num">${i+1}</div>
        <div class="uuid-text">${display}</div>
        <button class="uuid-copy" onclick="copyOne('${display}', this)">copy</button>
      </div>`;
    }).join('');
    document.getElementById('uuidList').innerHTML = html;
    document.getElementById('copyAllBtn').textContent = 'Copy All';
    document.getElementById('copyAllBtn').classList.remove('copied');
  }

  function copyOne(text, btn) {
    navigator.clipboard.writeText(text).catch(() => {});
    btn.textContent = 'copied!'; btn.classList.add('copied');
    setTimeout(() => { btn.textContent = 'copy'; btn.classList.remove('copied'); }, 2000);
  }

  function copyAll() {
    const fmt = document.getElementById('format').value;
    const text = lastUUIDs.map(u => applyFormat(u)).join('\n');
    navigator.clipboard.writeText(text).catch(() => {});
    const btn = document.getElementById('copyAllBtn');
    btn.textContent = 'Copied!'; btn.classList.add('copied');
    setTimeout(() => { btn.textContent = 'Copy All'; btn.classList.remove('copied'); }, 2000);
  }

  function showSpecial(type) {
    const val = type === 'nil' ? '00000000-0000-0000-0000-000000000000' : 'ffffffff-ffff-ffff-ffff-ffffffffffff';
    document.getElementById('specialOutput').textContent = `${type === 'nil' ? 'Nil' : 'Max'} UUID: ${val}`;
    navigator.clipboard.writeText(val).catch(() => {});
  }

  updateInfo();
  generate();