UTF‑8 to Base64 Converter

Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It is widely used to transmit binary data over text-based protocols such as email (MIME), HTTP, JSON, and XML. For example, images embedded in HTML or CSS via data URIs use Base64 encoding. Every 3 bytes of binary data are encoded into 4 Base64 characters, resulting in roughly a 33% size increase.

UTF‑8 is a character encoding that maps Unicode characters to variable-length byte sequences (1–4 bytes per character). When you encode UTF‑8 text to Base64, the text is first converted to its underlying UTF‑8 byte representation, and then those bytes are Base64-encoded. This ensures that all Unicode characters—including emojis, CJK characters, and accented letters—are correctly preserved. Our tool uses the browser's built-in TextEncoder API for accurate UTF‑8 byte conversion.

No. Base64 is not encryption—it is an encoding scheme. Anyone can decode Base64 back to the original data without any key or password. Base64 provides no confidentiality or security. It is simply a way to represent binary data in a text-friendly format. If you need to protect sensitive data, use proper encryption algorithms such as AES-256 or RSA, not Base64.

Yes! Since UTF‑8 can represent all Unicode characters (including emojis like 😊🌍🎉, CJK ideographs, Arabic script, and more), and Base64 can encode any byte sequence, the combination handles every character perfectly. Our tool correctly encodes a 4-byte emoji into its UTF‑8 bytes and then produces the corresponding Base64 output. Decoding reverses the process accurately.

Standard Base64 uses +, /, and = (padding), which have special meanings in URLs. URL-safe Base64 (also known as "base64url") replaces + with - and / with _, and optionally omits the = padding. Use URL-safe Base64 when embedding encoded data in URL paths, query parameters, or file names. Check the "URL-safe Base64" option in our tool to enable this variant.

Base64 encodes every 3 bytes (24 bits) of input into 4 characters (each representing 6 bits). The math is: 4/3 ≈ 1.333, which is a ~33.3% increase. Additionally, if the input length is not a multiple of 3, padding characters (=) are added to make the output length a multiple of 4, slightly increasing the overhead for small inputs. For example, 1 byte becomes 4 Base64 characters (300% overhead), while 3 bytes become exactly 4 characters (33.3% overhead).

Simply paste your Base64 string into the right panel (Base64 Encoded) of our tool, and the decoded UTF‑8 text will instantly appear in the left panel. You can also click the Swap button (↔) to reverse the direction. The tool automatically handles common formatting issues such as whitespace, line breaks, and URL-safe characters—so you can paste Base64 from virtually any source.

No. All encoding and decoding happens entirely in your browser using JavaScript. Your text never leaves your device—no data is uploaded, transmitted, or stored on any server. This makes the tool fast, private, and secure for sensitive content. You can even disconnect from the internet after the page loads and the tool will continue to work perfectly.

Common scenarios include: embedding images or fonts as data URIs in CSS/HTML; encoding credentials for HTTP Basic Authentication; transmitting binary data in JSON APIs; storing complex text in databases that only support ASCII; preparing email attachments (MIME); encoding cryptographic keys and signatures; and passing data through systems that may corrupt raw binary. Anywhere you need to safely transport data through a text-only channel, Base64 is the standard solution.

MIME (Multipurpose Internet Mail Extensions) specifies that Base64-encoded data in email should have line breaks every 76 characters. This prevents overly long lines that could cause issues with some mail servers or text editors. Enable this option if you're preparing content for email attachments or need strict MIME compliance. For most other uses (APIs, data URIs, URLs), you can leave it disabled for a compact single-line output.