Base64 Encoder Decoder
Encode plain text to Base64 or decode Base64 strings back to readable text with our free base64 encoder decoder. Supports both standard (RFC 4648) and URL-safe Base64 alphabets with full UTF-8 and emoji support. All base64 encoding and decoding runs locally in your browser - no signup required.
Encode plain text to Base64 or decode Base64 strings back to readable text. Supports standard and URL-safe alphabets. All processing runs locally in your browser - your data never leaves your device.
- Standard Base64 uses characters A-Z, a-z, 0-9,
+,/and=padding (RFC 4648) - URL-Safe Base64 replaces
+with-and/with_- safe for URLs and filenames (RFC 4648 §5) - Base64 increases data size by approximately 33% (3 bytes → 4 characters)
- Base64 is an encoding, not encryption - it provides no security on its own
Why Use Our Base64 Encoder Decoder?
Instant Base64 Encoding and Decoding
Encode plain text to Base64 or decode Base64 strings back to readable text instantly in your browser. Our base64 encoder decoder processes any input in milliseconds with zero wait time.
Secure Base64 Encoder Decoder Online
All base64 encoding and decoding happens locally in your browser. Your text and Base64 strings never leave your device, ensuring 100% privacy every time you use our base64 encoder decoder online.
Base64 Encoder Decoder - No Installation
Use our base64 encoder decoder directly in any browser with no downloads, plugins, or software required. Encode and decode Base64 from any device - desktop, tablet, or mobile - instantly.
Standard and URL-Safe Base64 Alphabets
Switch between standard Base64 (RFC 4648) and URL-safe Base64 (RFC 4648 §5) alphabets with one click. The URL-safe variant replaces + and / with - and _ for safe use in URLs and filenames.
Common Use Cases for Base64 Encoder Decoder
API Authentication Headers
Encode credentials for HTTP Basic Authentication headers using base64 encoding. The format username:password is base64-encoded and sent in the Authorization header for API requests.
JSON and REST API Payloads
Encode binary data or special characters as Base64 strings for safe inclusion in JSON payloads. Use our base64 encoder decoder to prepare and verify data before sending API requests.
Email and MIME Encoding
Base64 encoding is the standard for encoding email attachments and non-ASCII content in MIME messages. Encode text content to Base64 for safe transmission through email protocols.
JWT Token Inspection
Decode the header and payload segments of JWT tokens - each segment is Base64URL-encoded. Use our base64 encoder decoder with URL-safe mode to inspect JWT claims without a dedicated tool.
Data URI and Inline Assets
Encode small text assets to Base64 for embedding directly in HTML, CSS, or JavaScript as data URIs. This eliminates extra HTTP requests for small inline resources.
Debugging and Log Analysis
Decode Base64-encoded strings found in application logs, configuration files, and network captures. Our base64 encoder decoder instantly reveals the original content for debugging and analysis.
Understanding Base64 Encoding and Decoding
What is Base64 Encoding?
Base64 encoding is a method of representing binary data - or any arbitrary text - as a string of printable ASCII characters. It works by converting every 3 bytes of input into 4 characters drawn from a 64-character alphabet: A-Z, a-z, 0-9, and two additional symbols (+ and /in standard Base64). The name "Base64" comes from this 64-character alphabet. Our base64 encoder decoder implements the full RFC 4648 specification, including correct UTF-8 handling and optional padding. Base64 is not encryption - it is a reversible encoding that anyone can decode, so it should never be used to protect sensitive data on its own.
How Our Base64 Encoder Decoder Works
- Enter Your Input: Paste or type the plain text you want to encode, or paste the Base64 string you want to decode. Select the operation mode (Encode or Decode) and the alphabet (Standard or URL-Safe) from the dropdowns.
- Instant Browser-Based Processing: Click the action button and the base64 encoder decoder processes your input entirely in your browser using the built-in
btoa()/atob()APIs with full UTF-8 support. Your text never leaves your device. - Copy or Download the Output: The result appears instantly in the output box. Use the Copy button to copy it to your clipboard or the Download button to save it as a text file. Use Swap to flip the output back into the input for round-trip verification.
What the Base64 Encoder Decoder Handles
- Full UTF-8 Support: Correctly encodes multi-byte Unicode characters (emoji, CJK, Arabic, etc.) by converting to UTF-8 bytes before Base64 encoding.
- Standard Base64 (RFC 4648): Uses the standard alphabet with
+and/characters and=padding - the most widely supported format for email, MIME, and general data encoding. - URL-Safe Base64 (RFC 4648 §5): Replaces
+with-and/with_- safe for use in URLs, query strings, filenames, and JWT tokens without percent-encoding. - Automatic Padding Correction: Adds missing
=padding characters during decoding so that Base64 strings copied without padding still decode correctly.
Base64 vs. URL-Safe Base64 - When to Use Each
Use standard Base64 for email attachments, MIME encoding, HTTP Basic Auth headers, and any context where the output is not embedded in a URL. Use URL-safe Base64 when the encoded string will appear in a URL path, query parameter, cookie, filename, or JWT token - the - and _ characters do not need percent-encoding in these contexts, keeping strings clean and readable. Both variants produce the same length output and are equally reversible with our base64 encoder decoder.
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Frequently Asked Questions About Base64 Encoder Decoder
A Base64 encoder decoder is a tool that converts plain text or binary data into Base64-encoded strings and decodes Base64 strings back to their original content. Our base64 encoder decoder runs entirely in your browser - no signup, no server uploads, and no data stored anywhere.
No. Base64 is an encoding scheme, not encryption. It converts data into a different representation using a fixed 64-character alphabet, but anyone with a base64 encoder decoder can reverse it instantly. Never use Base64 alone to protect sensitive data - use proper encryption like AES for that purpose.
Absolutely. All Base64 encoding and decoding happens locally in your browser using JavaScript. Your text and Base64 strings are never sent to any server, stored, or logged. Your data stays completely private on your device.
Yes - our Base64 encoder decoder is 100% free with no signup, no account, and no usage limits. Encode and decode Base64 as many times as you need, for any amount of text, completely free forever.
Standard Base64 uses + and / as the 62nd and 63rd characters, which must be percent-encoded in URLs. URL-safe Base64 (RFC 4648 §5) replaces + with - and / with _ so the output is safe to use in URLs, query strings, filenames, and JWT tokens without any additional encoding.
Base64 encodes 3 bytes at a time into 4 characters. When the input length is not a multiple of 3, one or two = padding characters are added to make the output length a multiple of 4. Some implementations omit padding - our decoder handles both padded and unpadded input automatically.
Yes. Our base64 encoder decoder correctly handles the full Unicode range including emoji, CJK characters, Arabic, and other multi-byte scripts. It converts text to UTF-8 bytes first, then applies Base64 encoding - ensuring accurate round-trip encoding and decoding for any language.
JWT tokens consist of three Base64URL-encoded segments separated by dots (header.payload.signature). Copy the header or payload segment (the part before or between the dots), select URL-Safe mode in our base64 encoder decoder, choose Decode, and paste the segment to see the JSON content.
This usually means the original data was binary (an image, PDF, or other file) rather than plain text. Our base64 encoder decoder is designed for text content. For binary files, use the Base64/Hex File Encoder & Decoder tool which reconstructs the original binary file correctly.