How can I tell if a string is Base64 encoded?

Base64 strings contain only characters A-Z, a-z, 0-9, + and /. They often end with = or == (padding characters). String length is always divisible by 4. If you see this pattern — it's likely Base64.

What should I do if decoding gives an error?

Check the string for extra characters: spaces, line breaks, quotes. Make sure you copied the complete Base64 without truncation. Some systems add service characters — these need to be removed.

Can I decode an image from Base64?

Yes. If you have a Data URI like data:image/png;base64,... — paste only the part after "base64,". The tool will recognize the image and offer to download it in its original format.

Why won't the decoded file open?

The Base64 string may have been corrupted or truncated during copying. Also make sure you're opening the file with the right program. Check the extension — sometimes it needs to be changed manually.

How do I decode a JWT token?

JWT consists of three parts separated by dots. Each part (header, payload, signature) can be decoded separately. Paste one part — get JSON. But note: the signature doesn't decode to readable text.

Is it safe to decode unknown data?

Decoding happens in your browser, no data is sent to servers. But be careful: if you decode an unknown file, don't run it without scanning with antivirus.

What's the difference between Base64 and Base64URL?

Base64URL replaces + with - and / with _, and removes = characters. This is needed for safe use in URLs. Our decoder supports both variants automatically.

How do I decode Base64 from an email attachment?

Open the raw email source, find the Content-Transfer-Encoding: base64 block. Copy the text after the blank line (that's the Base64 attachment content) and paste it into the decoder. You'll get the original file.

Can I decode encrypted data?

Base64 is encoding, not encryption. If data was encrypted (AES, RSA), after decoding you'll get an encrypted binary blob, not the original text. You need a key and special tool for decryption.

How is the file type detected after decoding?

The tool analyzes "magic bytes" at the beginning of the file. For example, PNG starts with 89 50 4E 47, PDF with 25 50 44 46. These signatures determine the format and suggest the correct download extension.

Does the decoder work on mobile devices?

Yes. The interface is optimized for smartphones and tablets. Works in Safari, Chrome, Firefox on iOS and Android. You can paste Base64 from clipboard or upload a text file.

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Base64 Decode

Base64 Decode

Convert a Base64 string back to original text or file. The tool automatically detects data type and suggests the appropriate way to save it.

Encode to Base64

Base64 decoding use cases

API debugging and development

When working with REST APIs, you often need to decode Base64 responses: images, PDF documents, binary data. This tool helps you quickly check what the server returned without writing code.

Analyzing email and MIME attachments

Email attachments are encoded in Base64 per the MIME standard. If you need to extract a file from raw email or analyze an attachment — just paste the Base64 block and download the original file.

Extracting Data URIs

Images embedded in HTML via data:image/... can be extracted back. Copy the part after "base64," — get the original file. Useful when analyzing others' code or saving embedded graphics.

JWT token analysis

JSON Web Token consists of three Base64-encoded parts. Decode the header and payload to see token contents: signing algorithm, expiration time, user identifier, and other claims.

Recovering files from logs

Logging systems often save binary data as Base64. If you see a long Base64 string in logs — decode it to get the original file or data for troubleshooting.

How to decode Base64

Paste the Base64 string

Copy the encoded string and paste it into the text field. Or upload a text file containing Base64 content via the "File" tab.

Start decoding

Click "Decode". Processing happens instantly in your browser. The tool will automatically detect what was encoded — text, image, or other file.

Get your result

If it's text — copy it. If it's a file (image, PDF, archive) — download it. The original file format is fully preserved.

Base64 Encode

Encode text or files to Base64 in seconds. Browser-based processing, no registration, no l...

Encoders

URL Decode

Decode URL-encoded text back to readable form. Converts %20, %2F and other codes to normal...