Encodeur/Decodeur Base64 — Outil en ligne gratuit

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.

Comment l'utiliser Encodeur/Decodeur Base64

1. Open the Base64 tool.
2. Paste your text or Base64 string into the box.
3. Choose encode or decode.
4. See the converted result instantly.
5. Copy the output to use anywhere.

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