Base64 Encoder & DecoderEncode & Decode Anything Instantly

Base64 is a binary-to-text encoding scheme that converts binary data into a set of 64 ASCII characters (A-Z, a-z, 0-9, +, /). It's used when you need to transmit binary data through channels that only support text, such as embedding images in HTML/CSS with data URIs, sending email attachments via MIME, storing binary data in JSON payloads, encoding authentication tokens, and creating data URIs for web resources. Base64 increases data size by about 33% but ensures the data passes through text-only systems safely.

Our tool uses the browser's built-in btoa() function for encoding and atob() for decoding, with full Unicode support via encodeURIComponent/decodeURIComponent wrappers. When you type or paste text in Encode mode, the tool converts it to Base64 in real-time using auto convert. In Decode mode, it validates the Base64 format, detects the MIME type from magic bytes (e.g., /9j/ for JPEG, iVBOR for PNG), and shows the decoded result. For images, you get a live visual preview. Everything runs locally — no server calls.

Yes. In Encode mode, upload any text-based file (.txt, .json, .csv, .html, .css, .js, .xml) using the Upload button or drag-and-drop, and its contents will be loaded and encoded to Base64. In Decode mode, you can upload .b64 or .base64 files, or paste Base64 strings directly. The tool auto-detects the content type — if it's an image, you'll see a live preview. For binary files like PDFs or ZIPs, the tool detects the MIME type from the Base64 header so you know exactly what you're decoding.

When you paste a Base64 string in Decode mode, the tool examines the first few characters (known as "magic bytes") to determine the file type. /9j/ indicates a JPEG, iVBOR indicates a PNG, R0lGOD indicates a GIF, UklGR indicates WebP, JVBER indicates a PDF, and UEsDB indicates a ZIP file. When an image type is detected, the tool renders a live preview so you can verify the decoded content visually. The detected MIME type is displayed as a tag below the input area.

Absolutely. 100%. All encoding and decoding happens entirely in your browser using client-side JavaScript. Your text, files, and Base64 data are never uploaded, transmitted, stored, or logged on any server. We do not track, collect, or access your content in any way. The optional auto-save feature stores data in your browser's localStorage, which stays on your device. This makes the tool safe for encoding sensitive data like API keys, authentication tokens, personal documents, and proprietary code.

Yes. Once the page loads, you can disconnect from the internet and continue using all features — encode, decode, file upload, image preview, undo/redo, copy, download. Every operation runs locally with zero network requests. This is ideal for working on planes, in secure environments, or anywhere with unreliable connectivity. The only internet requirement is the initial page load.

The tool validates Base64 format in real-time and shows a validation indicator below the input. A green "Valid" badge means the format is correct. An amber "May be invalid" badge means the format doesn't pass basic checks — it might have invalid characters, wrong length, or incorrect padding. Even if the format is valid, the decoded result might not be readable text (e.g., binary data like images or encrypted content). In that case, the tool shows the raw decoded output. For images, a preview is displayed automatically.

Yes, our encoder handles full Unicode text including emoji, CJK characters, accented letters, and special symbols. We use the standard encodeURIComponent/decodeURIComponent wrapper around btoa/atob to properly handle multi-byte characters. This follows the recommended approach in the MDN Web Docs and ensures your international text is encoded and decoded correctly without corruption or data loss.