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Convert Base64 to Plain Text Decode Base64-encoded strings back to plain text instantly.

Base64 Decode illustration
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Base64 Decode

Decode Base64-encoded strings back to plain text instantly.

1

Paste Base64

Paste the Base64-encoded string into the input field.

2

View Decoded Text

The decoded plain text appears instantly in real time.

3

Copy Result

Click Copy to copy the decoded text to your clipboard.

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What Is Base64 Decode?

Decoding reverses the encoding process, converting a Base64-encoded ASCII string back into its original binary or text form. Each group of 4 encoded characters is converted back to 3 bytes of data. Padding characters (=) indicate the number of padding bytes at the end. This tool uses the browser's native atob() function with Unicode support via decodeURIComponent, correctly handling multi-byte UTF-8 characters, emoji, and international scripts. Invalid input is detected and reported with clear error messages. All processing happens entirely in your browser for maximum privacy and speed.

Why Use Base64 Decode?

  • Instant decoding with real-time output
  • Full Unicode and UTF-8 support for decoded text
  • 100% client-side processing — data never leaves your browser
  • Handles standard and URL-safe Base64 variants

Common Use Cases

Debug APIs

Decode Base64 payloads from JWT tokens, API responses, and webhooks.

Email Processing

Decode MIME-encoded email content and attachments.

Data Inspection

Inspect Base64-encoded configuration values and secrets.

Web Development

Decode data URIs and embedded Base64 content in web pages.

Technical Guide

Decoding maps each character back to its 6-bit value, reassembles the 6-bit groups into bytes, and strips any padding. The standard Base64 alphabet uses A-Z (0-25), a-z (26-51), 0-9 (52-61), + (62), / (63). Padding = characters indicate 1 or 2 missing bytes. This tool also accepts the URL-safe variant by replacing - with + and _ with / before decoding. After atob() produces a byte string, the tool reconstructs Unicode characters by reversing the UTF-8 encoding via decodeURIComponent(escape()).

Tips & Best Practices

  • 1
    Supports both standard and URL-safe Base64 input
  • 2
    Check for whitespace or line breaks in pasted Base64 strings
  • 3
    Use for debugging JWT tokens — the header and payload are Base64
  • 4
    Base64 is encoding, not encryption — anyone can decode it

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Frequently Asked Questions

Q Is this tool free?
Yes, completely free with no signup required.
Q Is my data secure?
Yes. All processing is 100% client-side in your browser.
Q Can it decode URL-safe Base64?
Yes, it handles both standard (+/) and URL-safe (-_) variants.
Q What browsers are supported?
All modern browsers including Chrome, Firefox, Safari, and Edge.
Q What if the input is invalid?
The tool shows a clear error message for invalid Base64 input.

About This Tool

Base64 Decode is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.