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Base64 Encoder & Decoder

Encode or decode base64 strings instantly. UTF-8 safe, runs locally in your browser — no upload, no signup.

  • Runs in browser
  • No signup
  • No tracking
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How to use Base64 Encoder & Decoder

  1. Pick Encode or Decode.

  2. Paste your input on the left.

  3. Result updates live on the right.

  4. Click Copy to grab the output.

When to use it

  • Embedding small images as data URIs.

  • Decoding the payload of a JWT.

  • Encoding credentials for HTTP Basic Auth.

  • Inspecting base64-encoded API responses.

What it fixes

  • Mojibake when btoa() chokes on UTF-8.

  • Padding errors from truncated base64.

  • Slow CLI round-trips for one-off encoding.

About Base64 Encoder & Decoder

Base64 is the standard binary-to-text encoding for embedding data in URLs, JSON, JWTs, data URIs, and email attachments. This tool handles both directions in your browser using native APIs.

UTF-8 support means emoji and non-ASCII text round-trip correctly — a common gotcha with raw btoa() that this tool wraps.

References: RFC 4648 — Base64 spec · MDN — btoa / atob

Frequently asked

  • Does it support UTF-8 / emoji?

    Yes. The tool round-trips emoji, accented characters, and any UTF-8 input correctly.

  • Is my data sent to a server?

    No. Encoding and decoding run with the native btoa/atob browser APIs. Your input never leaves the page.

  • What about base64url (URL-safe variant)?

    Standard base64 only. Replace + with - and / with _, and strip padding to get base64url manually.

Discussion

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