Base64 & URL Encoder — Free Online Tool

What Is Base64 & URL Encoder?

A free online Base64 and URL encoder/decoder. Convert text to Base64 or URL-encoded format, and decode back. Supports Unicode characters including emojis and CJK text. All processing happens locally in your browser.

Base64 encoding and URL encoding are fundamental techniques in web development, yet they can be surprisingly tricky to get right. Base64 converts binary data (images, files, encryption keys) into a safe text representation for embedding in HTML, CSS, or JSON. URL encoding replaces unsafe characters (spaces, symbols, Unicode) with percent-encoded sequences for use in query strings and URL paths. This tool handles both in a single interface, with full Unicode support and real-time conversion.

The tool offers four distinct modes accessible from a clean selector: Base64 encode, Base64 decode, URL encode, and URL decode. Type or paste your input and the output updates instantly — no submit buttons, no waiting. The swap button lets you reverse the operation immediately, which is invaluable for debugging: if you have an encoded string and need to see the original, or vice versa, one click switches directions. This instant feedback loop is much faster than switching between separate encode and decode pages.

Unicode support is a key differentiator. Many encoding tools fail on non-ASCII characters — they produce garbled output for emojis, Chinese characters, or accented letters. This tool uses the browser's native TextEncoder and TextDecoder APIs, which handle the full Unicode standard correctly. Whether you are encoding a Japanese kanji string for a URL parameter or decoding a Base64-encoded emoji, the result is always accurate.

All processing is local. Your data never leaves your browser — no server round-trips, no logs, no privacy concerns. This is especially important for sensitive operations like encoding API keys, JWT tokens, or authentication credentials where you would never want to paste the raw value into a server-side tool. The tool works even after the initial page load, since the encoding logic is built into the browser itself.

Real-World Use Cases for Base64 & URL Encoder

Debugging API Authentication Tokens

A JWT token from a login response is encoded in Base64. Paste the token into the Base64 decode mode to inspect its header and payload. Each segment is independently decodable, letting you verify the token contains the expected claims without writing any code.

Encoding Query String Parameters for Emails

E-commerce email links contain tracking parameters with spaces, special characters, or Unicode. Paste the product name or tracking ID into URL encode mode to generate a properly encoded query string that will not break when the recipient clicks the link.

Creating Data URIs for Inline Images

To embed a small icon directly in CSS or HTML without a separate HTTP request, encode the image file as a Base64 data URI. Upload the image or paste its binary content, encode it, and the result is ready to paste as a src="data:image/..." attribute.

Why Use Base64 & URL Encoder?

Four modes: Base64 encode/decode, URL encode/decode
Full Unicode support (emojis, CJK, etc.)
Instant real-time conversion
One-click swap to reverse encoding direction

How to Use Base64 & URL Encoder — Step by Step

Choose the mode: encode or decode, Base64 or URL.

Paste your text or encoded string into the input field.

The output updates instantly as you type.

Copy the result or swap input/output to reverse the operation.

Who Is Base64 & URL Encoder Best For?

API debugging
data URIs
URL parameters
JWT tokens

Pro Tips for Base64 & URL Encoder

1Swap between encode and decode with one click instead of navigating to a separate page. The swap button flips the mode and moves the output to the input — perfect for round-trip verification.
2When encoding URL parameters, only encode the value, not the entire URL. Encoding the whole URL (including the https:// and domain) will break it. Paste just the parameter value that needs escaping.
3Base64 encoding increases data size by approximately 33%. For large payloads, this matters — consider whether Base64 is necessary, or if the data can be transmitted in its original binary form.
4If the decoded output looks garbled, check whether you selected the correct mode. URL-decoded text that looks like Base64 probably needs Base64 decode instead, and vice versa.

Base64 & URL Encoder — Frequently Asked Questions

Does this support Unicode characters?

Yes, the tool properly handles UTF-8 encoding, so emojis, Chinese, Japanese, and other multi-byte characters work correctly.

Is my data sent to a server?

No. All encoding and decoding happens entirely in your browser. No data is ever transmitted to any server.

Can I use these tools with sensitive/proprietary data?

Absolutely. All processing runs locally in your browser with zero server uploads. This makes these tools safe for proprietary code, internal API keys, and confidential data.

Do these tools work offline?

Yes, once the page has loaded, most developer tools continue functioning without an internet connection. This makes them ideal for air-gapped environments or travel.

What browsers are supported?

All modern browsers are supported: Chrome, Firefox, Safari, and Edge. Internet Explorer is not supported. The tools leverage modern JavaScript APIs like Web Crypto, TextEncoder, and BigInt.

Ready to Use Base64 & URL Encoder?

Free online tool — works in your browser, no sign-up required. Start using it right now.

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