Free Online Base64 Encoder & Decoder
Base64 encoding and decoding are fundamental operations in modern software development, data transfer, and web APIs. Whether you need to encode text to Base64 for embedding in a JSON payload, decode a Base64 string received from an API, convert an image to a data URI for use in HTML or CSS, or verify the contents of an encoded file — our free Base64 encode decode tool handles all of these tasks instantly in your browser.
This all-in-one Base64 encoder online supports text input, direct file upload (images, documents, any binary), URL-safe mode, and line wrapping. The Base64 decoder online automatically detects image data URIs and renders a live preview alongside the decoded text output.
All processing uses JavaScript's native btoa() and atob() functions combined with the FileReader API. Nothing is ever uploaded, stored, or sent anywhere.
How to Use the Base64 Encode & Decode Tool
01
Choose Encode or Decode
Select the Encode tab to convert text or files to Base64, or Decode to convert a Base64 string back to text or a file.
02
Enter input or upload a file
Type or paste your content in the text area, or switch to the File tab and upload any file (up to 5 MB) for Base64 encoding.
03
Click the action button
Click Encode or Decode. Results appear instantly with file size stats, a ratio indicator, and an image preview for visual content.
04
Copy or download
Copy the output to your clipboard with one click, or download it as a .txt or .bin file directly from your browser.
What Is Base64 and Why Is It Used?
Base64 is a binary-to-text encoding scheme that represents binary data using only 64 printable ASCII characters: the letters A–Z and a–z, digits 0–9, and the symbols + and / (with = used for padding). It was standardised in RFC 4648 and is ubiquitous in modern computing.
Why Base64 encoding is needed
- Embedding images directly in HTML or CSS as
data:image/png;base64,… data URIs, eliminating extra HTTP requests
- Sending binary attachments (images, PDFs) inside JSON or XML payloads that only accept text
- Encoding email attachments via the MIME standard (used by every email client since the 1990s)
- Storing cryptographic keys, certificates, and tokens in text-based configuration files
- Transmitting arbitrary binary data through systems that only handle printable ASCII
Base64 is not encryption
A common misconception is that Base64-encoded data is "protected" or "hidden." It is not. Base64 is a reversible encoding — anyone can decode it in seconds with any Base64 decoder. Never use Base64 to secure sensitive information. For actual security, use proper encryption such as AES or RSA.
URL-safe Base64
Standard Base64 uses + and / characters, which are reserved in URLs and can break query strings or path segments. URL-safe Base64 (RFC 4648 §5) replaces + with - and / with _, making the output safe to embed in URLs without percent-encoding. Our tool supports both modes with a single checkbox toggle.
Tool Features at a Glance
⬆
Base64 Encoder
Encode any text string to Base64 instantly using the browser's native btoa() with full Unicode support.
⬇
Base64 Decoder
Decode any Base64 string back to text with clear error messages when the input is invalid or malformed.
📁
File to Base64
Upload any file (image, PDF, text, binary) and get its full Base64 representation with data URI prefix.
🖼️
Image Preview
When decoding Base64 image data, a live image preview renders automatically alongside the text output.
🔗
URL-safe Mode
One-click toggle between standard Base64 and URL-safe Base64 (-_ variant) for use in URLs and JWT tokens.
📊
Size Statistics
Input size, output size, and the size ratio shown instantly — Base64 typically adds ~33% overhead.
Frequently Asked Questions
What is Base64 encoding?▼
Base64 encoding converts binary data into a string of 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It is widely used to transmit binary data — images, files, cryptographic keys — through text-only channels such as JSON payloads, email, or HTML data URIs.
How to decode Base64 online?▼
Select the Decode tab, paste your Base64 string into the input area, then click Decode. The tool uses the browser's native atob() function and shows the decoded text instantly. If your Base64 string encodes an image, a live preview is displayed automatically below the output.
Is Base64 the same as encryption? Is it secure?▼
No. Base64 is an encoding scheme, not encryption. It provides zero security — anyone can decode it in seconds. Never use Base64 to protect sensitive data. For security, use proper encryption algorithms like AES-256 or RSA. Base64's purpose is data format compatibility, not confidentiality.
What is URL-safe Base64?▼
URL-safe Base64 (RFC 4648 §5) replaces the + character with - and / with _ to produce strings that can be safely included in URLs without percent-encoding. It is commonly used in JWTs (JSON Web Tokens), OAuth tokens, and any Base64 data embedded in query strings or URL paths.
Can I encode images to Base64?▼
Yes. Switch to the File tab, upload any image (PNG, JPEG, GIF, WebP, SVG), and the tool produces its full Base64 data URI. You can copy this to embed the image directly in HTML as <img src="data:image/png;base64,…"> or in CSS as a background-image, with no external file request required.
Is my data safe when using this tool?▼
Yes. All encoding and decoding runs entirely in your browser using JavaScript's native btoa() and atob() functions and the FileReader API. No data is sent to any server, stored, or logged. The tool works fully offline once the page has loaded.