CalcBrew

Base64 Encode & Decode

Paste text to get its Base64, or paste Base64 to read it back as text. Handles UTF-8 (accents, emoji), the URL-safe alphabet, 76-character MIME wrapping and data URIs, and can turn a small file into Base64 for embedding in HTML, CSS or JSON. Everything stays in your browser.

By Miikka · CalcBrew · Updated

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Encoded output

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How Base64 works

The encoder reads the input as bytes (UTF-8 for text), takes them three at a time — 24 bits — and splits those into four 6-bit numbers from 0 to 63. Each number maps to one character of the alphabet A–Z a–z 0–9 + /. “Hi” is the bytes 72 and 105, which is why it becomes SGk=: two bytes fill only 16 of 24 bits, so the last character is padding.

Hello, World! → SGVsbG8sIFdvcmxkIQ==

{"ok":true} → eyJvayI6dHJ1ZX0=

user:pa55word → dXNlcjpwYTU1d29yZA== (HTTP Basic auth)

Where you meet it: data URIs for inline images (src="data:image/png;base64,…"), JSON Web Tokens (three URL-safe Base64 segments separated by dots), email attachments (MIME, wrapped at 76 characters), Authorization: Basic headers and Kubernetes secrets.

Frequently asked questions

Cite this calculator
APACalcBrew. (2026). Base64 Encode & Decode Online. https://calcbrew.com/base64-encoder
MLA“Base64 Encode & Decode Online.” CalcBrew, 2026, calcbrew.com/base64-encoder.

Link to https://calcbrew.com/base64-encoder. Results are estimates; cite the underlying formula or data source for academic work.

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