Base64 Encode / Decode

Base64 is a binary-to-text encoding scheme that represents binary data as ASCII characters. It is commonly used to embed images in HTML/CSS, transmit data in URLs, and encode email attachments.

Yes. The tool properly handles multi-byte UTF-8 characters including emoji, CJK characters, and accented letters. It encodes and decodes them correctly.

Yes. All encoding and decoding happens locally in your browser. No data is sent to any server.

Yes. Switch to "File" mode using the tab at the top of the tool, select any file, and click "File → Base64". The full Base64 string is displayed and ready to copy. You can also paste a Base64 string in File mode and click "Base64 → Download File" to decode it back to binary.

Standard Base64 uses +, /, and = which have special meaning in URLs. URL-safe Base64 (Base64url) replaces + with - and / with _, and omits padding =. It is used in JWTs, OAuth tokens, and URL parameters. If you need URL-safe output, replace those characters after encoding.

Base64 increases data size by approximately 33%. Every 3 bytes of input become 4 characters of output. This overhead is why Base64 is not used for large file transfers, but is acceptable for tokens, short strings, and embedded images.

Yes. The interface is fully responsive. You can paste text, encode or decode, and copy results on any phone or tablet. File mode also works on mobile browsers that support file selection.

JavaScript's btoa/atob only handle ASCII and will break on multi-byte characters. The command-line base64 utility works well but requires a terminal. This tool handles full UTF-8 including emoji, CJK, and accented characters — no setup, no encoding workarounds.

Common use cases: embedding small images as data URIs in HTML/CSS, sending binary data in JSON payloads, encoding email attachments (MIME), transmitting data through text-only channels, and creating simple obfuscation (not security) for strings.

Yes. Paste the Base64 string (without the data:... prefix) in File mode, and click "Base64 → Download File" to reconstruct the binary file. For text content, use Text mode to decode the Base64 portion directly.

No. Base64 is an encoding scheme, not encryption. Anyone can decode a Base64 string — it provides zero security. Use it for data transport compatibility, not for hiding sensitive information. For actual encryption, use AES or similar algorithms.

The <a href="/ai/dev/jwt">JWT Decoder</a> works directly with Base64URL-encoded tokens. The <a href="/ai/dev/url-encode">URL Encoder</a> handles percent-encoding for URLs. The <a href="/ai/dev/hash">Hash Generator</a> produces fixed-length digests instead of reversible encodings.