What is Base64 encoding?

Base64 encodes binary data into ASCII text using 64 printable characters (A-Z, a-z, 0-9, +, /). It's used to embed binary data in text-based formats like JSON, XML, HTML, and email. The encoded output is roughly 33% larger than the input.

How do I encode text to Base64?

Paste your text in the input field and click Encode. The tool converts each character to its UTF-8 bytes and then to Base64 representation. Click Copy to grab the result.

When should I use Base64 encoding?

Common uses include: embedding small images in CSS/HTML (data URIs), sending binary data in JSON APIs, encoding file contents for upload, email attachments (MIME), and storing binary data in text-only databases.

What's the difference between Base64 and Base64URL?

Standard Base64 uses + and / characters, which need escaping in URLs. Base64URL replaces these with - and _ and removes padding (=). JWTs use Base64URL encoding because tokens are often passed in URLs.

Base64 кодирование

Кодирование и декодирование в браузере

Input

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Output

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Encode and decode Base64 without trusting an online server

Base64 shows up everywhere — JWT payloads, image data URIs, email attachments, API request bodies. Encoding and decoding it in your browser keeps the data on your machine, which matters when the value is a token, a secret, or anything else you'd rather not paste into a remote service.

Use the tool when you need to

Decode a Base64-encoded value from a header

Inspect Authorization headers, encoded query parameters, or other Base64 strings safely in the browser.

Encode binary data for an API

Convert a small image or file into a Base64 string for inclusion in a JSON request body.

Flip between Base64 and Base64URL

Switch encoding variants when working with JWTs and URL-safe payloads.

How to encode or decode Base64 quickly

1
Paste the input into the text area.
2
Click Encode or Decode based on the direction you need.
3
Copy the result, or download it as a file when working with binary data.

Keep going

Encode URL components

Use percent-encoding when the destination is a URL rather than binary safety.

Decode JWTs

Use the focused decoder when the Base64 value is part of a token.

Format decoded JSON

Beautify the output if the decoded value turns out to be JSON.

Validate decoded JSON

Confirm the decoded JSON parses cleanly before passing it forward.

Common Base64 workflows

Inspect an Authorization header

Decode a Basic auth header to see the raw username and password format being sent.

Embed a small asset in JSON

Encode a tiny image as a data URI and embed it directly in an API request body.

Round-trip token payloads

Decode a JWT segment, edit it, and re-encode it for testing — without server-side help.

Часто задаваемые вопросы

Base64 кодирует двоичные данные в ASCII-текст с помощью 64 печатных символов (A–Z, a–z, 0–9, +, /). Его используют, чтобы встраивать бинарные данные в текстовые форматы: JSON, XML, HTML и электронную почту. Размер результата примерно на 33% больше исходных данных.

Вставьте текст в поле ввода и нажмите «Закодировать». Инструмент переводит каждый символ в байты UTF-8, затем в представление Base64. Нажмите «Копировать», чтобы скопировать результат.

Типичные случаи: встраивание небольших изображений в CSS/HTML (data URI), передача бинарных данных в JSON API, кодирование содержимого файлов для загрузки, вложения в почте (MIME) и хранение бинарных данных в чисто текстовых БД.

Стандартный Base64 использует символы + и /, которые в URL нужно экранировать. Base64URL заменяет их на - и _ и убирает padding (=). В JWT применяется Base64URL, потому что токены часто передают в URL.