Base64 Decoder
Runs locally in your browser. Nothing leaves your device.Decode Base64, Base64URL, MIME Base64, or data URLs to bytes directly in the browser.
Decoder settings
Input
Output
Paste Base64 or choose a file to see the preview.
Paste Base64 or choose a file to see the preview.
How it works
- 1
Paste Base64 or choose a file
Paste Base64 text or choose a Base64 file.
- 2
Choose the decoding profile
Choose Auto-compatible or Standard strict and the desired text preview encoding.
- 3
Copy or download the result
Copy the text preview or download the decoded bytes as a file.
Good to know
The Base64 decoder decodes Base64, Base64URL, MIME Base64, and data URLs directly in your browser. Two profiles are available: Auto-compatible automatically detects data URLs and alphabet, Standard strict blocks whitespace and missing padding per RFC. Input is via pasted text or a file upload up to 100 MB.
Processing runs locally in the browser. Base64 is not encryption and should not be treated as protection for confidential content — anyone can decode Base64 without a password.
Typical use cases
Inspect data URLs and embedded content
Paste a data URL to inspect its media type and content, for example for images or fonts embedded in CSS or HTML.
Make Base64-encoded API responses readable
Decode Base64 fields from JSON responses or config files to inspect the contained text or bytes directly.
Convert Base64 files back to bytes
Upload a .b64 or .base64 file and download the decoded bytes as the original file, instead of converting manually.
Tips for better results
Deliberately choose Auto-compatible or Standard strict
Use Auto-compatible for everyday input with data URLs or a URL-safe alphabet, and Standard strict to specifically detect non-conforming Base64.
Match the text preview encoding to the content
If the text preview appears unreadable, check whether a different encoding fits the interpretation of the decoded bytes.
Features
Two decoding profiles
Auto-compatible automatically detects data URLs and alphabet; Standard strict blocks whitespace and missing padding.
MIME type detection
Automatically detects media type and MIME information from data URLs.
Local and private
Decoding runs entirely in the browser; your data never leaves your device.
Frequently asked questions
Is Base64 encryption?
No. Base64 is only an encoding; anyone can decode it without a password. It does not protect confidential content.
What's the difference between Auto-compatible and Standard strict?
Auto-compatible automatically detects data URLs and alphabet and is more tolerant; Standard strict blocks whitespace and missing padding per RFC.
Is my data uploaded?
No. Decoding runs entirely locally in the browser.
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