About Base64 Encoder & Decoder
Free Base64 encoder and decoder. Paste text to encode to Base64 or decode Base64 back to plaintext instantly. Supports UTF-8, binary data, and files — runs entirely in your browser.
How to use
- Paste or type the text you want to encode into the input field. Base64 encoding converts any text or binary data into a safe ASCII string using only letters (A-Z, a-z), numbers (0-9), plus (+), slash (/), and equals (=) for padding.
- Click Encode to convert your text to Base64. The encoded output will be approximately 33% larger than the input because Base64 uses 6 bits per character instead of 8, requiring 4 output characters for every 3 input bytes.
- To decode, paste a Base64 string into the input field and click Decode. The original text is restored exactly. Base64 decoding fails if the input contains invalid characters or has incorrect padding, and the calculator will show an error if the input is not valid Base64.
- Copy the result to your clipboard with one click. The encoded output is safe for embedding in JSON, XML, HTML, email bodies, URLs (with URL-safe variant), and API payloads where raw binary data would cause parsing issues.
- Use the file encoding option to encode images and small files as Base64 data URIs. A Base64-encoded image can be embedded directly in HTML or CSS:
. This eliminates an HTTP request at the cost of a 33% larger file size. - Toggle between standard Base64 (RFC 4648) and URL-safe Base64 (replaces + with - and / with _) depending on your use case. URL-safe Base64 is required when the encoded string will be used in URLs or filenames where + and / have special meanings.
Frequently asked questions
What is Base64 encoding?
Base64 is a binary-to-text encoding scheme that represents binary data as a string of printable ASCII characters. It encodes every 3 bytes of input into 4 Base64 characters, using an alphabet of 64 characters (A-Z, a-z, 0-9, +, /). It was designed for transmitting binary data through systems that only support text, such as email (MIME), JSON, XML, and URLs. Base64 is not encryption — it provides no security. Anyone can decode a Base64 string back to the original data. It is purely a data format conversion for transport compatibility.
When should I use Base64?
Common use cases: embedding small images directly in HTML/CSS to reduce HTTP requests, transmitting binary data in JSON APIs (which only support text), encoding file attachments in email (MIME encoding), storing binary data in text-only databases or configuration files, and encoding authentication credentials in HTTP Basic Auth headers. Avoid Base64 for large files (the 33% size increase is significant) or when the transport medium supports binary data natively. Base64 adds processing overhead for encoding and decoding, so use it only when direct binary transmission is not possible. To understand the underlying binary data you are encoding, use the Binary Converter to inspect values in binary, decimal, octal, and hex before encoding them.
Does Base64 provide encryption or security?
No. Base64 is encoding, not encryption. Anyone can decode a Base64 string instantly with no key or password. Do not use Base64 to hide sensitive information like passwords, API keys, or personal data. The encoding is trivially reversible. If you see a Base64 string in a URL or configuration file, it is not protected — decode it and the original data is fully readable. For actual security, use encryption algorithms like AES-256 for data at rest and TLS/HTTPS for data in transit. Base64 is often used to format encrypted data for text-based transport, but the Base64 layer itself adds no security.
Why does Base64 make data bigger?
Base64 converts every 3 bytes (24 bits) of input into 4 characters (24 bits in 6-bit groups), resulting in a 33% size increase. A 1 MB file becomes approximately 1.33 MB when Base64-encoded. This overhead occurs because Base64 uses only 64 of the 256 possible byte values, sacrificing space efficiency for character safety. Additional padding characters (=) may be added to make the output length a multiple of 4. For small data (under 10 KB), the overhead is negligible. For large files, the 33% increase matters — this is why Base64-encoded images in CSS are only recommended for very small icons and assets.
What is the difference between standard and URL-safe Base64?
Standard Base64 uses + and / characters which have special meanings in URLs (+ means space, / is a path separator). URL-safe Base64 replaces + with - (hyphen) and / with _ (underscore), making the encoded string safe for use in URLs, query parameters, and filenames without additional encoding. The padding character = is sometimes omitted in URL-safe variants since the padding can be inferred from the string length. Use standard Base64 for email, JSON, and API payloads. Use URL-safe Base64 for anything that will appear in a URL or filename.
How do I encode an image as Base64?
Use the file upload option to select an image, and the tool converts it to a data URI format: data:image/png;base64,iVBORw0KGgo... This string can be used directly as an img src or CSS background-image value. Benefits: eliminates an HTTP request for each image (faster initial page load for small images). Drawbacks: 33% file size increase, no browser caching (the image is re-downloaded with the HTML/CSS every time), and large Base64 strings bloat your code files. Best practice: only Base64-encode images under 10 KB (small icons, logos, decorative elements). Use regular image files for anything larger.
Can Base64 handle any type of data?
Yes. Base64 can encode any binary data: text in any character encoding (UTF-8, ASCII, Unicode), images (PNG, JPG, SVG, GIF), audio files, PDF documents, compressed archives, and raw binary streams. The encoding process treats the input as a sequence of bytes regardless of the content type. When decoding, the output is the exact same sequence of bytes as the original input. For text, ensure you know the original character encoding (usually UTF-8) to interpret the decoded bytes correctly. For files, the MIME type prefix in data URIs (data:image/png;base64,...) tells the browser how to interpret the decoded binary.
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