Base64 Decode Online, Free and Private
Decode Base64 to text or a file in your browser. Handles URL-safe Base64, missing padding and wrapped input, and names the first bad character. Nothing is uploaded.
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About decoding Base64
This page decodes Base64 back into text or a file, in your browser. Base64 shows up in email source, API responses, JWT tokens, data URLs, configuration files and log lines, and most of the time you just want to know what it says. Paste the string and the decoded text appears at once. When the bytes are not text, for example an image or a certificate, you get a download button instead of a screen of symbols. Nothing is uploaded, and your data never leaves your device.
How to decode Base64
Steps
- Paste the Base64 into the input. Line breaks, spaces, missing
=padding and adata:image/png;base64,prefix are all fine; the decoder strips them. - Read the result on the right. Text is shown as UTF-8, so accents and emoji come out as they were written.
- If the result is a file rather than text, press Download decoded file. The button shows how many bytes you will get.
- Press Copy to copy the decoded text.
Privacy
Decoding runs entirely in your browser. The Base64 you paste is never uploaded to our servers, and a decoded file is created on your device and forgotten when the tab closes.
Reading the error messages
Not a Base64 character
Base64 uses only letters, digits, +, / and =, or - and _ in the URL-safe variant. The decoder names the first character outside that set and its position, counted from the start of your input. The usual culprits are a stray quote, a trailing comma copied from JSON, or a line of text that was never Base64 at all.
Incomplete group
Base64 comes in groups of four characters. A string whose length leaves a single character at the end cannot be decoded, which almost always means the end was cut off while copying. Check that you have the whole value.
The result is not text
Valid Base64 that decodes to bytes which are not valid UTF-8 is binary data. That is normal for images, PDFs, archives and keys. Download the file and open it with the right program; the first few bytes usually tell you which, for example %PDF or PNG.
Where you meet Base64
- JWT tokens: three URL-safe Base64 parts separated by dots. Decode the first two to see the header and the payload.
- Data URLs:
data:image/png;base64,...in HTML and CSS. Paste the whole URL; the prefix is ignored. - Email: attachments and some message bodies carry
Content-Transfer-Encoding: base64. - Configuration and secrets: Kubernetes secrets, Docker auth files and many
.envvalues store bytes as Base64.
Related tools
Need to go the other way? The Base64 Encoder encodes text and files, with URL-safe and data URL options. Percent-encoded strings such as %20 belong in the URL Decoder. To inspect bytes as hex, decode here and then use Text to Hex, or verify a download against its checksum with the Hash Generator.