AnyFormat

00 Utility

Base64 Decode

Standard and URL-safe. Says so when the payload is not text.

01Input
02Output
  • No upload The conversion runs in this tab. Your file never travels — not to us, and not to the advertising.
  • No sign-up, no email, no daily cap There is no account system to sign up to.
  • No size limit we invented Only your device's memory — about ~2 GB on a desktop browser, ~400 MB on a phone.
  • Turn your Wi-Fi off and convert anyway The conversion needs nothing but this page. Ads will not load without a connection; your file will still convert. That is the whole claim, and it takes five seconds to check.

Paste Base64 and get the original text back. Both alphabets are accepted, padding is optional, and whitespace or newlines anywhere in the input are ignored — so pasting a wrapped blob straight out of a certificate or an email header works.

When the result is not text

A great deal of Base64 encodes bytes that were never text: a PNG, a PDF, a ZIP, an encrypted payload. Decoding those as text produces a screenful of replacement characters that tells you nothing.

Instead, the tool identifies the payload from its magic bytes and says what it is — "this decodes to a PNG image", "this is gzip-compressed data" — and points you at the right tool. Guessing from a wall of � is not a reasonable thing to ask of anyone.

Errors that name the problem

Three things go wrong with pasted Base64, and each gets its own message. A character outside the alphabet is usually a stray quote or a smart quote from a word processor — the offending character is quoted back to you. A length that is one more than a multiple of four means the string is truncated, which no encoder ever produces. Padding that does not reach a group boundary means characters were lost mid-copy.

Double encoding

If the output still looks like Base64, it probably is — encoding twice is a common accident in pipelines that Base64 a value that was already encoded. Just run it through again.

Other names for this

Also searched as “base64 decoder”, “decode base64 to text”, “base64 to string”.

Questions

It says my string contains an invalid character.
Almost always a smart quote or a stray space from copying out of a document. The tool quotes the exact character back to you.
The output is gibberish.
Then the payload is binary, not text — the tool will say what kind. Use the Base64 to Image tool if it is an image.
Does it accept the URL-safe alphabet?
Yes, automatically. It also accepts missing padding, so JWT segments decode without editing.
Does my text leave the browser?
No. Everything runs as JavaScript in this tab — there is no server involved and no request is made. Open the Network panel and watch, or turn your Wi-Fi off and keep using the tool.