Base64 Encoder & Decoder

How to Use the Base64 Encoder Decoder Online

1. Choose a mode - click "Encode" to convert plain text into a Base64 string, or "Decode" to reverse a Base64 string back to human-readable text.
2. Paste or type your input into the text area. The tool accepts any UTF-8 text, including emoji, accented characters, and non-Latin scripts.
3. Press the action button to run the conversion. The result appears immediately in the output field.
4. Copy the result with the one-click copy button, or hit Swap to move the output back into the input and reverse the direction.

About Base64 Encoding

Base64 is a binary-to-text encoding that represents any stream of bytes using only 64 printable ASCII characters: A-Z, a-z, 0-9, plus the symbols + and /, with = used as padding. Every three bytes of input are split into four 6-bit groups, and each group is mapped to one character from the alphabet. This means Base64 output is always about 33% larger than the original data.

The scheme was formalized in RFC 2045 as part of MIME (Multipurpose Internet Mail Extensions) so that binary attachments could survive passage through mail servers that only handle 7-bit ASCII. Today it powers data: URIs in CSS and HTML, JSON Web Tokens, HTTP Basic authentication headers, and many API payloads where raw bytes need to travel inside a text-only field.

Base64 is deliberately reversible and carries no secret: anyone holding a Base64 string can decode it instantly. It is therefore a transport encoding rather than a security primitive. If you need confidentiality, encrypt the data first with AES-GCM or a similar authenticated cipher and then Base64-encode the ciphertext for safe transmission through a text-only channel.

Base64 to UTF-8 and UTF-8 to Base64

The hardest thing about Base64 in the browser is not the encoding itself - it is making sure text stays correct after a round-trip. Browser built-ins btoa and atob only accept Latin-1 code points, so a naive encode of "naïve" or "こんにちは" throws InvalidCharacterError. This online Base64 encoder decoder solves that by running input through TextEncoder to turn the string into UTF-8 bytes before btoa, and running the output of atob through TextDecoder on the way back. That means Base64 to UTF-8 and UTF-8 to Base64 both work end-to-end on any Unicode input: emoji, Cyrillic, Arabic, Chinese, Japanese, combining accents, right-to-left marks, zero-width joiners - all of it survives the conversion unchanged.

Why Use an Online Base64 Encoder Decoder

• Debugging a data: URL you pulled out of HTML, CSS, or a browser "Copy image as data URL" right-click - paste the payload and see what it decodes to.
• Inspecting the payload of a JSON Web Token: JWT splits its three segments with "." and Base64url-encodes each, and this encoder decoder (with a dash-to-plus swap) reads them.
• Preparing an HTTP Basic authentication header: Base64 encode the literal string user:password and drop the result after "Basic " in the Authorization header.
• Passing binary payloads inside JSON fields that only accept strings - convert base 64 online is how a PNG thumbnail or a small certificate rides inside an API request.
• Embedding a small SVG icon or web font directly in HTML/CSS with a data URI to save an HTTP request on the critical path.
• Reading a MIME email attachment that was encoded with "Content-Transfer-Encoding: base64" and decoding it back to bytes.

Examples

• Text Hello becomes SGVsbG8=. The trailing = is padding because the input length is not a multiple of three bytes.
• Text Man (three bytes, no padding needed) becomes TWFu.
• Emoji 👋 (four UTF-8 bytes) becomes 8J+Riw==, demonstrating that multi-byte characters encode correctly.

Base64 vs URL Encoding

Base64 and URL (percent) encoding solve different problems and are not interchangeable. Base64 takes arbitrary bytes and produces a 7-bit ASCII string using a 64-character alphabet, with a roughly 33 percent size overhead. URL encoding takes a string and replaces only the characters that are unsafe inside a URL component (space, &, ?, #, non-ASCII bytes) with %XX sequences. URL encoding leaves safe ASCII alone, so the overhead for plain English text is near zero. The shortcut: use Base64 when you need to put binary data inside a text-only field (JSON body, HTTP header, data URL); use URL encoding when you need to put a string into a URL query parameter, path segment, or form body. The URL encoder and decoder handles the latter case. Note also Base64url (RFC 4648 section 5), a URL-safe Base64 variant that swaps + and / for - and _ and drops trailing padding - it is what JWT and many OAuth flows use.

Base64 to Text and Text to Base64 in the Same Tool

Most users land here looking for "base64 to text" or "text to base64" - both are the same encode/decode pair. Pick Encode to convert text to a Base64 string, or Decode to turn a Base64 string back to readable text. The output mirrors what command-line base64 on macOS or Linux produces, so paste the result of echo -n "Hello" | base64 here and you will get Hello back. For the inverse direction, the result matches echo "SGVsbG8=" | base64 -d. Need to encrypt the text first so the Base64 output is meaningless without a key? Run it through the AES encrypt and decrypt tool, then Base64-encode the ciphertext here. To inspect a Base64-encoded JWT segment, decode it with the JWT decoder, which handles the URL-safe Base64url variant automatically.

Convertitore Base64 online

Questo convertitore Base64 online esegue la codifica e la decodifica direttamente nel tuo browser: incolla il testo UTF-8 per ottenere una stringa Base64, oppure incolla una stringa Base64 per riottenere il testo originale senza perdere accenti, emoji o caratteri non latini. Non serve registrazione, nessun file viene caricato su un server e il risultato appare immediatamente. Ideale per preparare un header HTTP Basic, ispezionare un data URL, leggere un payload JWT o inserire un piccolo asset in HTML o CSS. Supporta Unicode completo grazie a TextEncoder e TextDecoder.

Convertisseur Base 64 en ligne

Ce convertisseur Base 64 en ligne encode vos chaînes UTF-8 en Base64 et décode en sens inverse, entièrement dans votre navigateur. Collez le texte à encoder ou la chaîne à décoder, le résultat s'affiche instantanément et rien n'est envoyé à un serveur. L'outil gère parfaitement les accents, les emoji, l'arabe, le chinois et tout autre caractère Unicode, sans l'erreur habituelle d'InvalidCharacterError. Pratique pour inspecter un JWT, générer une en-tête HTTP Basic, lire un message MIME ou intégrer un actif inline via un data URL.

Convertir Base 64 online

Convertir Base 64 online nunca fue tan simple: pega tu texto UTF-8 para obtener una cadena Base64 lista para un payload JSON, un encabezado HTTP Basic o un data URL, o pega una cadena Base64 para recuperar el texto original. Todo el proceso sucede en tu navegador, sin subir nada a ningún servidor y sin registro. El codificador y descodificador Base64 admite Unicode completo - emojis, tildes, cirílico, chino y árabe - gracias al uso interno de TextEncoder y TextDecoder, así que no aparecen los errores típicos de btoa.