Encode and decode Base64 and URL strings. Fast, secure, and works entirely in your browser.
This tool lets you encode and decode Base64 and URL-encoded strings instantly, right in your browser. Whether you are a developer working with API tokens, a designer embedding images as data URIs, or a student learning about web encoding standards, this encoder and decoder handles everything quickly and privately with no server required.
Base64 is a binary-to-text encoding scheme that represents binary data using a set of 64 printable ASCII characters — the letters A–Z and a–z, the digits 0–9, and the symbols + and /. It was designed to allow binary data to be safely transmitted over text-based protocols that might otherwise misinterpret raw binary bytes. The name "Base64" comes from the fact that the encoding uses a 64-character alphabet.
Base64 encoding works by taking three bytes of binary data (24 bits) and splitting them into four groups of six bits each. Each six-bit group is then mapped to one of the 64 characters in the Base64 alphabet. This means that Base64-encoded data is always approximately 33% larger than the original binary data, which is a trade-off for the ability to safely transmit binary content as plain text.
Base64 is not encryption — it is simply an encoding scheme. Anyone who has the Base64-encoded string can decode it back to the original data without any key or password. It should never be used to secure sensitive information on its own. Its purpose is data representation and safe transmission, not security.
URL encoding, also known as percent-encoding, is a method of encoding special characters in URLs so they can be safely transmitted over the internet. URLs can only contain a limited set of characters — letters, digits, and a few special characters like hyphens and underscores. Any other character must be encoded as a percent sign followed by two hexadecimal digits representing the character's ASCII code. For example, a space becomes %20, an ampersand becomes %26, and a question mark becomes %3F.
URL encoding is essential when including user-generated content, search queries, or special characters in URL parameters. Without it, characters like &, =, and ? would be interpreted as URL syntax rather than data, breaking the URL structure. Proper URL encoding ensures that query strings and path segments are transmitted correctly regardless of their content.
Like Base64, URL encoding is fully reversible — decoding a URL-encoded string always produces the original text. It is a standard part of web development and is used extensively in form submissions, API calls, OAuth flows, and any situation where data needs to be included in a URL.
Using this tool is simple and requires no technical knowledge beyond knowing which encoding type you need.
Base64 and URL encoding are fundamental tools in web development and are used in a wide variety of everyday scenarios.
When working with Base64-encoded data, be aware that the encoded string will always end with one or two equals signs (=) as padding characters, unless the original data length is a multiple of three bytes. If you see a Base64 string without padding, it may have been generated using the Base64url variant (used in JWTs), which replaces + with - and / with _ and omits padding. This tool handles standard Base64; for Base64url, you may need to add padding manually before decoding.
For URL encoding, note that encodeURIComponent (used by this tool) encodes all special characters except letters, digits, and the characters - _ . ! ~ * ' ( ). This is the correct function to use for encoding individual query parameter values. If you need to encode an entire URL while preserving its structure, use encodeURI instead, which does not encode characters that have special meaning in URLs like /, ?, and #.
Remember that neither Base64 nor URL encoding provides any security. If you need to protect sensitive data, use proper encryption. Base64 is often mistaken for encryption because it makes data unreadable at a glance, but it is trivially reversible by anyone. Never use Base64 to "hide" passwords, API keys, or other sensitive information in client-side code.
Webutilbox's encoder/decoder is fast, free, and completely private. Unlike many online tools that process your data on a server, this tool runs entirely in your browser. Your text, tokens, and encoded strings never leave your device, which is especially important when working with authentication tokens, API keys, or other sensitive data that you need to inspect or debug.
The auto-convert feature makes the tool particularly efficient for iterative work — as you type or paste, the output updates instantly without any button clicks. The size statistics for Base64 conversions give you useful context about the overhead of encoding, which is helpful when optimizing data URIs or evaluating the impact of Base64 encoding on payload size in API responses.
Your privacy is our priority. All processing happens entirely in your browser using JavaScript. No files, data, or inputs are ever uploaded to any server. Everything stays on your device, making this tool completely safe to use with sensitive content.