Base64 Decode is a free tool that converts Base64 back into its original form. Text is shown directly; images, PDFs and other files are recognised automatically and can be previewed or downloaded. It accepts standard and URL-safe Base64 as well as data URLs, and it runs entirely in your browser.
How to decode Base64
- Paste the Base64 into the left box. Line breaks and spaces are ignored.
- If it contains text, the decoded text appears on the right.
- If it contains a file, you’ll see what kind of file it is, a preview for images, and a Download file button.
Examples
SGVsbG8sIHdvcmxkIQ==→Hello, world!SGVsbG8sIHdvcmxkIQ(padding missing) →Hello, world!, since missing=is added automaticallydata:image/png;base64,iVBORw0KGgo…→ a PNG image you can preview and download
Recovering files from Base64
Base64 is often used to carry files inside emails, JSON responses and web pages. This tool looks at the first bytes of the decoded data to recognise PNG, JPEG, GIF and WebP images, PDFs, ZIP archives (including Word and Excel files, which are ZIPs internally) and GZIP files, and gives the download the right file extension.
Why decoding fails
- Invalid character: something other than Base64 was copied, such as quotes around the value or a label like
key=. Remove it and try again. - Incomplete: the Base64 was cut off. Copy the whole value; long Base64 is easy to truncate.
- Mixed variants: the text contains both
+ /(standard) and- _(URL-safe) characters, so it was probably damaged.
Standard and URL-safe Base64
Standard Base64 uses + and /. URL-safe Base64 (used in JWTs and web addresses) replaces them with - and _, and often leaves off the = padding. Both are detected automatically. To look inside a JWT specifically, the JWT Decoder decodes all of its parts and explains the claims.
Frequently asked questions
Why do I get a file instead of text?
Base64 can hold any kind of data. If the decoded bytes are not readable text, the tool recognises common formats such as PNG, JPEG, PDF and ZIP, shows a preview for images, and lets you download the file.
Why does it say a character is invalid?
Base64 only uses A–Z, a–z, 0–9, + and / (or - and _ in URL-safe Base64), with = at the end. Spaces and line breaks are ignored automatically, but anything else usually means some extra text was copied along with the Base64.
Can I paste a data URL?
Yes. Text such as data:image/png;base64,iVBOR… is recognised, and the part before the comma is removed automatically.
Is my data uploaded?
No. Decoding happens in your browser, and decoded files are created on your device when you download them.
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