Numarly

Base64 / URL Encoder-Decoder

Encode or decode text as Base64 or a URL component, instantly.

What is it?

This tool encodes and decodes text using either Base64 or URL percent-encoding, showing both results at once so you can convert in either direction from a single input.

Formula Explanation

Base64 encoding converts binary data into a 64-character alphabet (A-Z, a-z, 0-9, +, /), commonly used to safely embed data in text-based formats like JSON or HTML. URL encoding (percent-encoding) instead replaces unsafe or reserved characters — spaces, symbols, non-ASCII characters — with a %XX escape sequence so text can be safely used inside a URL.

Example Calculation

The text Hello, World! encodes to SGVsbG8sIFdvcmxkIQ== in Base64, and to Hello%2C%20World! in URL encoding.

How to Use

  1. Choose Base64 or URL mode using the tabs.
  2. Type or paste your text into the Input box.
  3. The Encoded box shows your input converted to that format.
  4. The Decoded box shows what your input would be if it were already encoded text.

Benefits

  • Shows encoding and decoding side by side, so you don't need to switch tools depending on direction.
  • Supports both Base64 (for data embedding) and URL encoding (for safe URLs) in one place.
  • Runs entirely in your browser, so sensitive text never leaves your device.

Use Cases

  • Encoding a string to safely include in a data URL or API payload.
  • Decoding a Base64 token or JWT segment to inspect its contents.
  • Encoding a query parameter value that contains spaces or special characters for a URL.

What Your Result Means

If the Decoded box shows an error, your input likely isn't valid encoded text in that mode — Base64 decoding fails on invalid characters or padding, and URL decoding fails on malformed percent-escape sequences.

Tips

  • Base64-encoded text is about 33% longer than the original — expect that size increase when embedding it elsewhere.
  • Use URL encoding only for the parts of a URL that need it (like a query value), not the entire URL, or you'll break the structure.
  • Base64 is not encryption — anyone can decode it back to the original text.

Common Mistakes

  • Assuming Base64 encoding is a form of security or encryption — it's fully and easily reversible.
  • URL-encoding an entire URL including the scheme and slashes, which breaks it instead of making it safe.
  • Trying to Base64-decode text that isn't actually Base64, which produces garbled or invalid output.

FAQs

Does this tool send my text to a server?

No, all encoding and decoding happens locally in your browser using built-in JavaScript functions.

Is Base64 encoding secure?

No, Base64 is just a reversible encoding scheme, not encryption — anyone with the encoded text can decode it back to the original.

Why does my Base64 output end with an = sign?

The = characters are padding, added when the input length isn't a multiple of 3 bytes, so the encoded output aligns to the required 4-character blocks.

What's the difference between encodeURIComponent and Base64?

URL encoding escapes only the specific characters unsafe in a URL, while Base64 re-encodes the entire input into a different character set, regardless of what it will be used for.

Encoding and decoding happen locally in your browser and your text is never sent to a server.

Last updated: July 27, 2026