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TinySolve

Base64 Decoder

Decode Base64 back to text, accepting URL-safe input, missing padding and stray whitespace.

Runs in your browser — nothing you type is sent anywhere

Decoded text

The result appears here as you type. Nothing is sent anywhere — the work happens in this page.

About the Base64 Decoder

Base64 turns up everywhere a system needs to move data through a text-only channel: an API response, an email header, a configuration file, the middle section of a JWT. Decoding it by hand is impossible, and most of the time you simply want to see what is in there.

Real Base64 in the wild is rarely tidy. Copied out of an email it has line breaks through it; taken from a URL it uses the URL-safe alphabet with hyphen and underscore; pulled from a token it has had the padding stripped off. All three are accepted here without you having to clean anything up first.

When something cannot be decoded, the reason is spelled out rather than left as a browser error. There are three distinct failures and they mean different things: the value contains characters Base64 never uses, the value is truncated so the last group is incomplete, or it decoded successfully to bytes that are not text at all — which usually means it is an image or a compressed file rather than something readable.

That last check matters. Decoding without it produces a string full of replacement characters that looks like a successful result, and people then spend time wondering why the output is gibberish instead of being told the data was never text.

Everything runs in your browser, which is the point when the Base64 you are inspecting is the payload of a real session token.

How to use the Base64 Decoder

  1. Paste the Base64

    Standard or URL-safe, padded or not, with or without line breaks. Whitespace is ignored, so you can paste straight from wherever you found it.

  2. Read the decoded text

    The result appears immediately on the right. There is no button and nothing is submitted anywhere.

  3. Check the message if it fails

    The error says which of the three things went wrong: invalid characters, truncated data, or content that is binary rather than text.

  4. Copy what you need

    Copy the decoded text to your clipboard, or download it as a file.

Frequently asked questions

Why does my Base64 fail to decode?
Usually one of three reasons: it contains characters Base64 never uses, it has been truncated so the final group is incomplete, or it is not text at all. The error message tells you which, rather than leaving you with a generic failure.
Do I need to add the padding back?
No. Missing equals signs are restored automatically, which matters because JWTs and URL-safe Base64 routinely strip them. Line breaks and spaces are ignored too.
Can it decode URL-safe Base64?
Yes, automatically. Hyphen and underscore are recognised as the URL-safe equivalents of plus and slash, so you can paste a JWT segment or a value from a query string without converting it first.
What does 'decoded to binary data' mean?
The Base64 was valid but the bytes inside are not text — typically an image, a PDF or compressed data. Rather than showing a string of replacement characters that looks like a broken decode, the tool says plainly that the content is not text.
Is it safe to decode a token here?
The decoding happens entirely in your browser and nothing is transmitted, so no value you paste reaches us. Bear in mind that decoding a token does not verify it, and that a token pasted anywhere at all is worth treating as exposed.

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