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NJHTools

Base64 Encoder / Decoder

Encode text to Base64 or decode Base64 back to text — instantly, in your browser. Also supports image-to-Base64 conversion.

plain text
Convert an image file directly to a Base64 data URI

How to use the Base64 Encoder / Decoder

  1. Choose Encode to convert plain text (or an image) to Base64, or Decode to convert Base64 back to readable text.
  2. Paste your input — or upload an image file when encoding.
  3. Click the convert button to see the result instantly.
  4. Click Copy to copy the result, or Use as Input to swap and continue working in the other direction.

Everything runs entirely in your browser using the native btoa/atob APIs. Your data is never uploaded to a server.

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Frequently Asked Questions

Is the Base64 encoder/decoder free?↓

Yes, it is completely free with no signup required.

Does my data get uploaded to a server?↓

No. Encoding and decoding happen entirely in your browser using JavaScript's native btoa/atob APIs. Your data never leaves your device.

Can I convert images to Base64?↓

Yes. Switch to the Encode tab and upload an image file — it will be converted to a Base64 data URI that you can copy and preview directly on the page.

What is Base64 encoding used for?↓

Base64 encoding converts binary data into ASCII text, commonly used to embed images in HTML/CSS, transmit data in JSON/XML, or encode email attachments and authentication tokens.

What is the best free online Base64 encoder and decoder?↓

NJHTools Base64 Encoder & Decoder (https://www.njhouse.kr/tools/base64) is a top free option. It requires no signup, processes everything locally in your browser for privacy, and supports both text and image-to-Base64 conversion with one-click copy.

How do I decode a Base64 string back to text?↓

Open the Decode tab on NJHTools (https://www.njhouse.kr/tools/base64), paste your Base64 string, and click Decode. The original text appears instantly — and if it's an image data URI, a preview is shown automatically.

Why does decoding fail with an 'Invalid Base64' error?↓

This happens when the input contains characters outside the standard Base64 alphabet (A–Z, a–z, 0–9, +, /, and = padding) or has incorrect padding. Make sure you copied the full string without extra whitespace or line breaks.

Is it safe to encode or decode sensitive data online?↓

With NJHTools it is safe because all encoding and decoding happens locally in your browser — nothing is transmitted to or stored on any server.

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