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Last updated: April 13, 2026

JWT Decoder for Svelte Developers

Quick Answer

DevToolHQ's jwt decoder works great alongside Svelte. Use it to quickly jwt decoder during development, then integrate the pattern into your Svelte codebase using the code example below.

Use Cases in Svelte

  • 1.Verify user authentication tokens
  • 2.Debug token expiration and claims
  • 3.Implement role-based access control from JWT claims
  • 4.Validate tokens from third-party auth providers

Svelte Code Example

Svelte
<script lang="ts">
  let token = $state('')

  const payload = $derived(() => {
    try {
      const p = JSON.parse(atob(token.split('.')[1].replace(/-/g,'+').replace(/_/g,'/')))
      return JSON.stringify(p, null, 2)
    } catch { return 'Invalid JWT' }
  })
  const expired = $derived(() => {
    try { return JSON.parse(atob(token.split('.')[1])).exp < Date.now()/1000 }
    catch { return false }
  })
</script>

<textarea bind:value={token} rows={3} placeholder="Paste JWT..." />
<pre>{payload()}</pre>
{#if expired()}<p style="color:red">⚠️ Token expired</p>{/if}

Try the tool directly

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Open Jwt Decoder

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