What is Base64 encoding?

Base64 is an encoding scheme that converts binary data into a string of printable ASCII characters. It represents every 3 bytes of binary data as 4 characters from a 64-character alphabet (A–Z, a–z, 0–9, +, /). The name comes from the 64 distinct characters used. Base64 is not encryption — anyone can decode it — it is purely a way to safely transmit binary data through text-based systems like email or JSON APIs.

What is the difference between encoding and decoding Base64?

Encoding converts raw text or binary data into a Base64 string. Decoding reverses the process: it takes a Base64 string and converts it back to the original data. For example, encoding 'Hello' produces 'SGVsbG8='; decoding 'SGVsbG8=' produces 'Hello'. The trailing = or == characters are padding that ensures the output length is a multiple of 4.

What is URL-safe Base64?

Standard Base64 uses '+' and '/' characters, which have special meaning in URLs. URL-safe Base64 (also called Base64url) replaces '+' with '-' and '/' with '_', making the encoded string safe to use in URL parameters and filenames without percent-encoding. JWT tokens use URL-safe Base64 encoding.

Why does Base64 increase data size by about 33%?

Base64 encodes every 3 bytes as 4 characters. Since each character is 1 byte in ASCII, 3 bytes becomes 4 bytes — a 33% size increase. This overhead is the tradeoff for having a safe, text-compatible representation of binary data.

When should I use Base64?

Use Base64 when you need to embed binary data inside a text format: embedding images in CSS (data URIs), including binary data in JSON or XML payloads, encoding email attachments (MIME), or storing small binary blobs in databases that only accept strings. Do not use it as a security measure — it is trivially reversible and provides zero confidentiality.

Encoding & Conversion

Base64 Encode / Decode

Encode text to Base64 or decode Base64 to text — runs entirely in your browser.

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Base64 — frequently asked questions

URL Encode / Decode

Encode or decode URL components with percent-encoding support.

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Hash Generator

Generate MD5, SHA-1, SHA-256, and SHA-512 hashes in your browser.

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Image to Base64

Convert images to Base64 encoded strings — nothing leaves your browser.

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