🔣 Base64 Encoder/Decoder
Encode or decode Base64 strings
About the Base64 Encoder and Decoder
Base64 is an encoding scheme that converts binary data into a string of printable ASCII characters. It was designed to solve a specific problem: many systems that transport text, such as email protocols and XML documents, cannot safely handle raw binary data or certain control characters. Base64 encodes any data into a safe alphabet of 64 characters, making it transportable through systems that only understand plain text.
This Base64 Encoder and Decoder handles both directions. Paste plain text or a binary-derived string and encode it to Base64. Paste a Base64 string and decode it back to the original. The tool works entirely in your browser, so no data is sent to any server, which matters when you are encoding anything remotely sensitive like configuration values or credentials used in development.
Base64 is everywhere in modern web development. HTTP Basic Authentication sends credentials as a Base64-encoded string in the Authorization header. Data URIs embed images directly in HTML or CSS using Base64-encoded image data, eliminating a network request. JSON Web Tokens, known as JWTs, use URL-safe Base64 to encode their header and payload sections. Email attachments are Base64-encoded by MIME before transmission.
It is important to understand that Base64 is encoding, not encryption. Anyone who has the encoded string can trivially decode it back to the original. It provides no confidentiality. Its purpose is to make data safe for text-only transport channels, not to protect it from being read. Do not use Base64 as a security measure for anything sensitive in production systems.
The encoded output is always about 33 percent larger than the input because every three bytes of input become four ASCII characters of output. This size overhead is worth noting when Base64-encoding large files or images inline into CSS, as it can meaningfully increase file size compared to linking external assets.
How it works
- Paste your plain text or binary-derived content into the input field.
- Click Encode to convert it into a Base64 string.
- To decode, paste a Base64 string into the input and click Decode.
- The result appears instantly in the output area.
- Copy the encoded or decoded output with the copy button.
- Use URL-safe mode if your output will appear in a URL or JWT context.
What you'll learn
- Base64 encodes binary data into 64 printable ASCII characters for safe text transport.
- The encoded output is roughly 33 percent larger than the original input.
- Base64 is encoding, not encryption, and provides zero security or confidentiality.
- HTTP Basic Auth, JWTs, data URIs, and email attachments all use Base64.
- URL-safe Base64 replaces + with - and / with _ to avoid conflicts in URLs.
- Decoding is always lossless and returns the exact original input.
FAQs
- Is Base64 the same as encryption?
- No. Base64 is a reversible encoding that anyone can decode instantly. It provides no security whatsoever. Never use it to protect passwords, tokens, or confidential data in production.
- What is the difference between standard Base64 and URL-safe Base64?
- Standard Base64 uses + and / as part of its alphabet, which have special meaning in URLs. URL-safe Base64 replaces + with - and / with _ so the output can appear safely in query parameters and JWT headers.
- Why is Base64 output longer than the input?
- Base64 converts every 3 bytes of input into 4 output characters, adding padding as needed. This results in output that is approximately 33 percent larger than the original data.
- Can I encode images or files with this tool?
- This tool is optimized for text and string-based input. For full binary file encoding, a dedicated file-to-Base64 converter that reads raw bytes from a file upload is more appropriate.
- Why do some Base64 strings end with one or two equals signs?
- The equals sign is a padding character added when the input length is not a multiple of three bytes. One or two padding characters may appear at the end of the encoded string to complete the final four-character block.