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Base64 Decoder

Decode Base64 back to readable UTF-8 text, including URL-safe input.

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The Base64 Decoder turns a Base64 string back into the original readable text it represents. It is the natural companion to our Base64 Encoder and is invaluable whenever you receive Base64 data in an API response, a JSON Web Token segment, a data URI, an email header or a configuration file and you simply need to see what the value actually contains.

This tool is designed for developers debugging integrations, support teams reading encoded log values, and anyone who has come across a wall of Base64 and wants the plain text behind it. It is deliberately tolerant: it accepts both the standard alphabet and the URL-safe variant, strips surrounding whitespace and line breaks, and restores any missing equals padding automatically.

The decoded bytes are interpreted as UTF-8, so text in any language, including emoji and non-Latin scripts, is restored correctly without corruption. All processing happens locally in your browser using JavaScript, which means the input you paste and the decoded result are never uploaded, logged or stored on a remote server at any point.

Features of Base64 Decoder

  • Automatically decodes both standard Base64 and the URL-safe variant without requiring you to choose a mode.
  • Interprets decoded bytes as UTF-8 so emoji, accents and international scripts are restored accurately every time.
  • Strips surrounding whitespace and newlines so pasted multi-line values decode cleanly without manual cleanup.
  • Restores any missing equals padding automatically before decoding so trimmed strings still work correctly.
  • Provides clear, specific error messages when the input is not valid Base64 or has an incorrect length.
  • Displays the decoded character count so you can quickly confirm the size of the recovered content.
  • Offers one-click copy and a text-file download to move the decoded text straight into your work.
  • Runs fully client-side in your browser, so nothing you paste is ever sent to or kept on any server.

How to use Base64 Decoder

  1. Paste the Base64 string you want to decode into the input box, including multi-line or URL-safe values.
  2. Alternatively, upload a plain text file in the accepted .txt format to load a longer encoded string.
  3. Watch the decoded, human-readable text appear instantly in the output area as soon as the input is valid.
  4. If you see an error message, check for stray characters or a truncated string and correct the source.
  5. Confirm the result using the decoded character count shown alongside the recovered output text.
  6. Copy the decoded text to your clipboard or download it as a text file for use elsewhere.

Benefits of Base64 Decoder

  • Developers can inspect Base64 payloads from APIs, tokens and data URIs quickly during debugging sessions.
  • Support and operations teams can read encoded values that appear inside logs, configs and exported records.
  • Integration engineers can verify exactly what an encoder produced and confirm round-trip correctness fast.
  • QA testers can confirm that encoded fields contain the expected content before signing off on a release.
  • Privacy-conscious users can decode sensitive values locally without trusting any external or remote service.
  • Anyone curious about a mysterious Base64 string can reveal its plain-text meaning in a single paste.

Base64 turns up everywhere in modern software: JWT headers and payloads, inline image data URIs, email MIME parts, signed cookies and encoded configuration values. This decoder lets you peek inside any of them without writing a script. Paste the value, read the plain text, and you immediately understand what an API, token or config file is actually carrying.

If decoding fails, the two most common causes are extra characters that are not part of the Base64 alphabet and a truncated string whose length is invalid. The tool reports these conditions explicitly so you can trace the problem back to the source, fix the copied value, and decode it successfully on the next attempt.

All decoding runs entirely in your browser, so the strings you paste, which may contain sensitive tokens, are never uploaded or retained anywhere. Remember that Base64 is only an encoding and not encryption, so a value being decodable does not mean it was ever secret; treat any credentials you reveal here with the same care you would the originals.

Questions about Base64 Decoder

Does this decoder accept URL-safe Base64?
Yes. It automatically converts hyphen back to plus and underscore back to slash, then restores any missing equals padding, so both the standard alphabet and the URL-safe variant decode correctly without you needing to select a mode beforehand.
Why do I get an invalid Base64 error?
The input either contains characters outside the Base64 alphabet or has a length that cannot form whole bytes. Remove any stray symbols, confirm nothing was cut off when copying, and make sure the entire encoded string was pasted into the box.
Is my data uploaded anywhere?
No. Decoding happens entirely in your browser using JavaScript, so the Base64 you paste and the plain text it produces never leave your device. Nothing is transmitted to a server, logged or stored, which makes the tool safe for sensitive values.
Can it decode non-English text?
Yes. The decoded bytes are interpreted as UTF-8, so emoji, accented letters and non-Latin scripts such as Greek, Hebrew or Japanese are all restored correctly, exactly matching whatever original text was encoded before it became a Base64 string.
Can I decode a JWT with this tool?
You can decode the individual header and payload segments, which are Base64URL encoded, by pasting each part between the dots separately. The tool reveals the JSON inside, though it does not verify the token's signature or check whether it has expired.
Does it handle line breaks in the input?
Yes. The decoder strips whitespace and newlines before processing, so Base64 that was wrapped across multiple lines, as often happens in emails and PEM files, decodes correctly without you having to join the lines together first.
How do I decode Base64 to plain text?
Paste the complete Base64 value into the input box and read the decoded result that appears below it. The decoder accepts standard and URL-safe Base64, restores missing padding and interprets the recovered bytes as UTF-8 text.
Can this Base64 decoder decode an image or file?
It is designed to display Base64 that represents UTF-8 text, including JSON, tokens and data embedded in code. It does not reconstruct binary files for download, so use a file-aware decoder when the value represents an image, PDF or other binary file.
How your data is handled: This tool runs entirely in your browser. Nothing is uploaded or stored on our servers.

More decoding tools to try

Base64 Encoder

Encode text to Base64 instantly, with optional URL-safe output.

Open Base64 Encoder

URL Decoder

Decode percent-encoded URLs and query strings back to plain text.

Open URL Decoder

JWT Decoder

Decode a JWT's header and payload without verifying the signature.

Open JWT Decoder

URL Encoder

Percent-encode text for URLs, with component and full-URI modes.

Open URL Encoder

Guides and related topics for Base64 Decoder

Glossary

What is Base64 Encoding?

Base64 is an encoding scheme that represents binary data using 64 printable ASCII characters so it can travel safely through text-only channels.

Comparison

Base64 vs URL Encoding

Base64 vs URL encoding: binary-to-text versus safe URL characters. Learn what each does, why they're not interchangeable, and when to use them.