Base64 Encoder / Decoder
Encode or decode Base64 instantly. Supports standard and URL-safe variants. Real-time output, one-click copy, and swap direction. 100% client-side โ your data never leaves the browser.
20 chars
Uses +, /, and = padding. Best for email (MIME), data URIs, and JSON-embedded files.
Replaces + with -, / with _, and drops = padding. Safe for URL params, JWT tokens, and filenames.
Base64 FAQ
What is Base64 encoding?
Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters: AโZ, aโz, 0โ9, +, and /. It was designed to safely transmit binary data (like images or files) through systems that only handle text, such as email (SMTP) and HTTP headers. The name 'Base64' comes from the 64-character alphabet used. Every 3 bytes of input become 4 Base64 characters, so the output is about 33% larger than the original.
What is the difference between Standard and URL-safe Base64?
Standard Base64 uses + and / as the 62nd and 63rd characters and pads the output with = signs. Both + and / are special characters in URLs and can cause parsing errors if not percent-encoded. URL-safe Base64 (also called Base64url) replaces + with - (hyphen) and / with _ (underscore), and drops the = padding entirely. This makes it safe to include directly in URL query parameters, JWT tokens, and filenames without any escaping.
What is Base64 used for in web development?
Data URIs: embedding images or fonts directly in HTML/CSS as base64-encoded strings (data:image/png;base64,...). JWT tokens: the header and payload of a JWT are base64url-encoded JSON objects. HTTP Basic Auth: credentials are sent as base64(username:password) in the Authorization header. API responses: some APIs return binary files (PDFs, images) as base64 strings inside JSON. Email attachments: MIME-encoded email attachments use Base64 to embed files in plain-text email format.
Is Base64 a form of encryption?
No. Base64 is an encoding scheme, not encryption. It provides zero security โ anyone who can see the Base64 string can trivially decode it back to the original. It is used for safe transmission format, not confidentiality. Never use Base64 to 'hide' passwords, API keys, or sensitive data. For actual security, use HTTPS for transport, and AES-256 or similar for data at rest.
Why does the output have = at the end?
Base64 encodes every 3 bytes into 4 characters. If the input length is not a multiple of 3, one or two = padding characters are added so the output length is always a multiple of 4. This makes it easier for decoders to determine where the data ends. URL-safe Base64 typically omits the padding because the decoder can infer the correct length from the total output length.
Is this tool safe for sensitive data?
Yes โ all encoding and decoding happens entirely in your browser using JavaScript's built-in btoa() and atob() functions. No data is transmitted to any server. The tool has no network requests. That said, Base64 is not encryption โ if you are handling truly sensitive data, use proper end-to-end encryption rather than just encoding.