JWT Decoder / Encoder
Decode payloads, verify signatures, test secrets, and generate JWT tokens.
Free Base64 Encoder & Decoder
Encode or decode Base64 strings instantly. Supports Base64URL variant and file upload.
Input
What is Base64?
Base64 is a binary-to-text encoding scheme that converts data into an ASCII string format. It is commonly used in email attachments, data URLs, API authentication, and embedding binary data in text-based formats like JSON and XML.
How to Use This Tool
- Paste text or Base64 into the input field, or drag-and-drop a file
- Click Encode to convert text to Base64, or Decode to convert Base64 back to text
- Enable the Base64URL toggle for URL-safe output (replaces +/ with -_ and strips padding)
- The tool auto-detects when your input looks like Base64
Common Use Cases
- Encoding images for inline data URIs in HTML/CSS
- Encoding credentials for HTTP Basic Authentication headers
- Transmitting binary data through JSON APIs
- Decoding Base64-encoded email attachments
Tips and Common Mistakes
- Base64 is encoding, not encryption — it provides no security
- Base64 output is ~33% larger than the original data
- Use Base64URL for tokens and URLs to avoid issues with + and / characters
- If decoding fails, check for missing padding (= characters) at the end
FAQs
Why is Base64 output about 33% larger than the input?
Base64 encodes every 3 bytes of input into 4 ASCII characters (6 bits per character). This 4/3 ratio means the output is always roughly 33% larger than the original binary data, plus optional padding characters.
What is the difference between Base64 and Base64URL?
Standard Base64 uses + and / characters and = for padding. Base64URL replaces + with -, / with _, and typically strips the = padding. Base64URL is safe for use in URLs and filenames without additional encoding.
Is Base64 encoding the same as encryption?
No. Base64 is an encoding scheme, not encryption. Anyone can decode a Base64 string without a key. It is designed for safe transport of binary data over text-based protocols, not for security.
Can I encode binary files (images, PDFs) to Base64?
Yes. Base64 is commonly used to embed images in HTML/CSS via data URIs and to transmit binary attachments in email (MIME) and JSON APIs. This tool supports text-to-Base64; for files, use the drag-and-drop upload.
What are the = signs at the end of a Base64 string?
The = characters are padding. Base64 output must be a multiple of 4 characters. If the input byte count is not divisible by 3, one or two = signs are appended to reach the correct length.
Is Free Base64 Encoder & Decoder Online — Text & File Support free to use?
Free Base64 Encoder & Decoder Online — Text & File Support is completely free and runs in your browser.
Does Free Base64 Encoder & Decoder Online — Text & File Support send my data to a server?
No. Free Base64 Encoder & Decoder Online — Text & File Support processes input directly in your browser.
Do I need to create an account to use Free Base64 Encoder & Decoder Online — Text & File Support?
No account is required to use Free Base64 Encoder & Decoder Online — Text & File Support.
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