Base64 Encoder/Decoder — Free Online Tool
Use instantly, free, with no signup. Your files are processed locally and never uploaded.
By the AllFileBox Team · Last updated: 2026-06-22
Base64 is a free online tool that encodes text into Base64 and decodes Base64 back into readable text in your browser, a common task for embedding data and transmitting binary safely.
What Base64 is for
Base64 represents binary or text data using 64 safe ASCII characters, so it can travel through systems that only handle text, such as email, JSON, and data URLs. It is how images get embedded directly in HTML, how credentials are passed in some headers, and how binary attachments survive text-only channels. Encoding does not encrypt; it only re-represents data.
Encoding increases size
Because Base64 turns every three bytes into four characters, the encoded output is about 33 percent larger than the original data. That overhead is the price of text safety. For that reason you encode only when a channel requires plain text, and you decode back to the original whenever you need the real bytes for storage or display.
Encode and decode both ways
The tool converts in both directions: paste plain text to get its Base64 form, or paste a Base64 string to recover the original. This is handy for inspecting a data URL, decoding the readable parts of a token, or preparing a small asset to inline in code. Invalid Base64 input is flagged so you know the string is malformed.
Private and local
Base64 runs entirely in your browser. Your text is encoded or decoded locally and is never uploaded or stored, so sensitive strings and tokens stay on your device. There is no server involved, the conversion is instant, and closing the tab clears your data from memory.
How To Use Base64 Encoder/Decoder
- Open the Base64 tool.
- Paste your text or Base64 string into the box.
- Choose encode or decode.
- See the converted result instantly.
- Copy the output to use anywhere.
Inline a small image
Inline a small image
Encode a tiny icon to Base64 so you can embed it directly in HTML or CSS as a data URL.
Inspect a token
Decode the readable segments of a Base64 string to check what data it contains.
Pass text safely
Encode a snippet so it survives a channel that only accepts plain ASCII text.
| Property | Detail | Note |
|---|---|---|
| Alphabet | 64 characters | A-Z, a-z, 0-9, + and / |
| Size change | About 33% larger | Three bytes become four |
| Purpose | Text-safe transport | Not encryption |
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Key Features Base64 Encoder/Decoder
Your Files Stay Private
All processing happens in your browser using WebAssembly. Your file is never sent to our servers. We have zero access to your files — guaranteed.