Encodeur / Décodeur Base64
Encodez et décodez des chaînes Base64 instantanément — collez du texte pour l'encoder, ou collez du Base64 pour le décoder en texte brut.
À propos de Base64
Base64 est un schéma d'encodage qui convertit des données binaires en texte ASCII. Il est couramment utilisé pour intégrer des ressources binaires dans du JSON, encoder des données dans des URL et transmettre des données via des protocoles textuels. Cet outil gère le texte Unicode complet via l'encodage UTF-8.
FAQ
- Base64 est-il un chiffrement ?
- Non. Base64 est un encodage, pas un chiffrement. N'importe qui peut le décoder. Ne l'utilisez jamais pour protéger des données sensibles.
- Mes données sont-elles envoyées à un serveur ?
- Non. Tout le traitement se fait localement dans votre navigateur.
- Cela prend-il en charge Unicode ?
- Oui. L'encodeur utilise UTF-8 en interne, donc tous les caractères Unicode sont gérés correctement.
- À quoi sert le bouton inverser ?
- Déplace le résultat vers l'entrée et change le mode — utile pour effectuer rapidement un aller-retour de données.
À PROPOS DE CET OUTIL
Paste any text to encode it into Base64, or paste a Base64 string to decode it back to plain text. Base64 represents binary data using 64 printable ASCII characters (A–Z, a–z, 0–9, + and /, with = padding), which is why it's the standard way to embed images, fonts, or files inside text-based formats like JSON, HTML, or email. Because it encodes 3 bytes as 4 characters, encoded output is always roughly 33% larger than the original. Commonly used when working with email attachments, authentication tokens, or embedding binary data in JSON and HTML — this tool runs entirely client-side, so sensitive tokens never leave your browser.
COMMENT UTILISER
- Choose Encode or Decode mode.
- Paste your plain text (to encode) or Base64 string (to decode) into the input box.
- Click convert, or let it convert automatically as you type.
- Review the output — decoding invalid Base64 shows an error instead of garbled text.
- Copy the result to your clipboard.
- For files or images, convert them to a Base64 string elsewhere first, then paste here to inspect or re-encode.
CAS D'USAGE COURANTS
- A developer embedding a small icon as a data URI in CSS needs to Base64-encode the image file's bytes.
- Someone inspecting the payload of a Basic Auth header decodes the "Authorization: Basic xxxx" string to see the username and password.
- An engineer debugging an email system decodes a Base64-encoded attachment or body part from raw MIME.
- A developer storing binary blobs in a JSON field encodes them first since JSON has no native binary type.
- A student verifying how much larger encoded output gets compares byte counts before and after encoding.
CONSEILS ET ERREURS COURANTES
- Base64 is encoding, not encryption — anyone can decode it, so never use it as a way to protect secrets or passwords.
- Standard Base64 uses + and / characters, which aren't URL-safe; if you're decoding a token from a URL, look for "Base64url" variants that use - and _ instead.
- Decoding fails or produces garbage if the input has incorrect padding (=) or contains characters outside the Base64 alphabet.
- Expect encoded text to be about 33% larger than the original, since every 3 bytes of input becomes 4 characters of output.
AUTRES QUESTIONS
- Is Base64 the same as encryption?
- No. Base64 only re-represents bytes as text with no key or secret involved, so it provides zero confidentiality — anyone can decode it instantly.
- Why is my JWT or URL token not decoding correctly here?
- Many tokens use Base64url encoding, which replaces + with -, / with _, and often omits padding — if standard decoding fails, try the URL-safe variant.
- Why does encoded text look longer than the original?
- Base64 converts every 3 bytes of binary input into 4 ASCII characters, inflating size by roughly 33%, plus padding characters at the end.
- Can I Base64-encode an entire image file here?
- This tool works on text and Base64 strings; for a raw file you'd typically convert it to Base64 first using a file-to-base64 step, then paste the resulting string here to inspect or manipulate it.