Base64 Encoder & Decoder Online Free
Base64 Encoder / Decoder is a free online tool that converts plain text or files to Base64 — and back — entirely in your browser. It supports standard and URI-safe Base64, auto-detects whether your input is already encoded, and lets you upload any file to get its Base64 representation without sending anything to a server.
How to Encode or Decode Base64 Online
- 01
Enter text or upload a file
Type or paste a plain-text string into the input area, or click "File to Base64" to select any file from your device. The tool auto-detects whether your input looks like Base64 and switches modes accordingly.
- 02
Choose Encode or Decode
Select Encode to convert plain text to a Base64 string, or Decode to reverse the process. Enable "URI-safe output" if you need the result embedded in a URL.
- 03
Copy or swap the result
Click Copy to put the output on your clipboard. Use Swap to move the output back to the input for chaining operations. All processing happens instantly in your browser.
Features
- ✓Encode text to Base64 instantly
- ✓Decode Base64 back to plain text
- ✓URI-safe / Base64url output option
- ✓File to Base64 conversion (any file type)
- ✓Auto-detect encode vs. decode mode
- ✓Swap input and output with one click
- ✓100% client-side — nothing leaves your browser
- ✓No login, no file upload, no sign-up
Frequently Asked Questions
What is Base64 encoding?
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 embed binary content — such as images, audio, or files — inside text-based formats like JSON, XML, HTML, or email attachments.
Is Base64 a form of encryption?
No. Base64 is encoding, not encryption. It does not protect data — anyone can decode a Base64 string instantly with any decoder. If you need to protect data, you need a real encryption algorithm such as AES. Base64 is purely for safe transport of binary data through text-only channels.
What is URI-safe Base64?
Standard Base64 uses the characters + and / and = as padding, which have special meaning in URLs. URI-safe (also called Base64url) replaces + with -, / with _, and omits the = padding. This makes the encoded string safe to embed in URLs and query parameters without additional percent-encoding.
How does file to Base64 conversion work?
When you upload a file, the browser reads it as a binary data URL using FileReader, then extracts the Base64 portion. The file is never sent to a server — all conversion happens inside your browser tab. This is useful for embedding images directly in CSS or HTML as data URIs.
Why does decoding fail for some strings?
Base64 decoding fails when the input contains characters outside the valid Base64 alphabet, or when the string length is not a multiple of 4 (after accounting for padding). The tool shows an error message explaining what went wrong. Make sure the string has not been modified or truncated.