Frequently Asked Questions

URLP is a free collection of online developer tools for encoding, decoding, and formatting data. All tools run directly in your browser, ensuring fast processing and complete privacy. No data is sent to our servers.

No, all tools are completely free and require no registration or account creation. Simply visit the tool you need and start using it immediately.

Yes, absolutely! All URLP tools are completely free to use with no limitations. We support the site through non-intrusive advertising.

While you need an internet connection to load the page initially, all processing happens in your browser using JavaScript. Once loaded, the tools work without sending data to our servers.

Base64 encoding converts binary data into ASCII text format. Use it when transmitting binary data over text-based protocols (email, JSON APIs), embedding images in HTML/CSS, or storing binary data in text formats. Remember: Base64 is not encryption!

URL encoding (percent encoding) makes text safe for use in URLs by converting special characters to %XX format. Base64 converts any data into a text format using A-Z, a-z, 0-9, +, and /. Use URL encoding for query parameters and Base64 for binary data transmission.

HTML entity encoding prevents XSS attacks by converting special characters (<, >, &, etc.) into safe entities (&lt;, &gt;, &amp;). Always use it when displaying user-generated content on websites to prevent security vulnerabilities.

JWT (JSON Web Token) is a secure way to transmit information between parties. Our JWT decoder splits the token into its three parts (header, payload, signature) and decodes the header and payload. Note: This tool does not verify signatures - always verify JWTs on your server.

Yes! All processing happens entirely in your browser. Your data never leaves your device or gets sent to our servers. However, avoid using sensitive production tokens or credentials in shared or public environments.

No. Since all processing happens in your browser using JavaScript, we never receive, store, or log any data you enter into our tools. Your privacy is completely protected.

Yes! All URLP tools are free to use for both personal and commercial projects without restrictions. No attribution required.

URLP tools work in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. We recommend keeping your browser up to date for the best experience. The tools use standard JavaScript APIs (btoa/atob, encodeURIComponent, TextEncoder) supported by all browsers released in the last 5 years. Even older browsers like Internet Explorer 11 can run most tools, though we recommend modern browsers for the best performance and security.

When you use a URLP tool, JavaScript code embedded in the webpage performs the encoding or decoding operation. For example, Base64 encoding uses the browser's built-in btoa() function or Buffer API in modern browsers. URL encoding uses encodeURIComponent(). JSON formatting uses JSON.parse() and JSON.stringify(). All these are native browser APIs that execute entirely on your device. No AJAX requests, no WebSockets, no server communication. Just local JavaScript execution. You can verify this by opening your browser's Network tab in Developer Tools and watching that no requests are made when you click "Encode" or "Decode".

Base64 is encoding, not encryption, because it's easily and instantly reversible without any secret key. Anyone can decode Base64 with freely available tools (including this website). Encryption requires a secret key and uses complex mathematical algorithms (like AES or RSA) that are computationally infeasible to reverse without the key. Base64 simply converts binary data to text using a fixed alphabet (A-Z, a-z, 0-9, +, /). There's no security involved. Never use Base64 alone to protect sensitive data like passwords or API keys. Always use proper encryption first, then optionally Base64 encode the encrypted result if you need text format.

encodeURIComponent() encodes everything except A-Z, a-z, 0-9, -, _, ., ~, *, (, ). Use it for encoding query parameter values. encodeURI() preserves URL structural characters like :, /, ?, &, =, allowing you to encode an entire URL while keeping it functional. For example, encodeURIComponent("http://example.com?q=test") encodes the colon and slashes, breaking the URL structure. encodeURI() would preserve them. For URLP and most developer use cases, encodeURIComponent() (which our tool uses) is correct because you're encoding individual values, not complete URLs.

URLP tools can handle reasonably large text inputs (up to several megabytes) depending on your device's RAM and browser performance. However, very large files (100MB+) may cause performance issues or browser memory errors since all processing happens in your browser's JavaScript environment. For extremely large files, consider using server-side processing or command-line tools. As a guideline, most text-based data (JSON responses, configuration files, code snippets) works perfectly. Large binary files (videos, high-resolution images) should be processed server-side or with native applications.

Standard Base64 uses the alphabet A-Z, a-z, 0-9, +, / with = for padding. Base64URL (<a href="https://www.rfc-editor.org/rfc/rfc4648.html#section-5" rel="nofollow noopener" target="_blank">RFC 4648 Section 5</a>) replaces + with - and / with _ (URL-safe characters) and typically omits padding (=). This makes Base64URL safe for use in URLs, file names, and HTTP headers without additional encoding. JWT tokens use Base64URL encoding. Use standard Base64 for general encoding and Base64URL specifically when the encoded string will appear in a URL or file name. Our Base64 tools use standard Base64, but the decoded result of Base64URL will work correctly since the character sets overlap.

Non-ASCII characters (accented letters, Chinese, Arabic, emoji) must be converted to UTF-8 bytes before encoding. Modern browsers handle this automatically. When you paste unicode text into our tools, JavaScript's TextEncoder API converts it to UTF-8 bytes before encoding. When decoding, TextDecoder converts UTF-8 bytes back to unicode text. If you see garbled output, the most common issue is encoding/decoding with different character sets (e.g., encoding as ISO-8859-1 but decoding as UTF-8). Always use UTF-8 encoding for maximum compatibility and internationalization support.

Named entities use human-readable names: &lt; for <, &gt; for >, &amp; for &, &quot; for ". Numeric entities use character codes: &#60; for <, &#62; for >, &#38; for &. Both produce the same result in browsers. Named entities are limited to predefined characters (about 252 in HTML5), while numeric entities can represent any Unicode character (&#x1F600; for 😀). Our HTML encoder primarily uses named entities for common characters because they're more readable in source code. Numeric entities are used for characters without named equivalents.

The most common JSON errors are: (1) Trailing commas after the last array item or object property. JSON forbids these while JavaScript allows them. (2) Single quotes instead of double quotes. JSON requires double quotes for strings and property names. (3) Unquoted property names like {name: "value"}. JSON requires {"name": "value"}. (4) Comments. JSON has no comment syntax, though some parsers allow them. (5) Undefined, NaN, Infinity values. JSON only supports strings, numbers, booleans, null, arrays, and objects. Use our JSON Formatter to identify the exact error location and get helpful error messages.

Base64 strings must only contain A-Z, a-z, 0-9, +, / and = (for padding). Common causes of invalid Base64 include: (1) Extra whitespace, newlines, or carriage returns. Remove all whitespace. (2) Wrong characters like @ or $ that aren't in the Base64 alphabet. (3) Truncated string. Base64 length must be a multiple of 4 (padding with = makes this true). (4) Accidentally pasted non-Base64 text. (5) Using Base64URL (- and _ characters) with a standard Base64 decoder. Copy only the encoded portion without any surrounding text, remove whitespace, and ensure the string ends properly.

There are two URL encoding standards: (1) <a href="https://www.rfc-editor.org/rfc/rfc3986.html" rel="nofollow noopener" target="_blank">RFC 3986</a> percent encoding encodes spaces as %20. This is used in URL paths and modern query strings. Our URL Encoder uses this standard. (2) application/x-www-form-urlencoded (form encoding) encodes spaces as +. This is used by HTML forms with GET method. Both are valid, but + is only for form data, while %20 works everywhere. When decoding, most decoders handle both formats. When encoding, use %20 for general URL encoding (our tool) and + specifically for form submissions.

Our JWT decoder is for inspection only. It doesn't verify signatures. For production use, always verify JWT tokens on your server using a proper JWT library: (1) PHP: firebase/php-jwt library with JWT::decode($token, $key, ['HS256']). (2) Node.js: jsonwebtoken library with jwt.verify(token, secret). (3) Python: PyJWT library with jwt.decode(token, secret, algorithms=['HS256']). (4) Java: java-jwt or nimbus-jose-jwt libraries. Verification checks include: (a) signature is valid, (b) token hasn't expired (exp claim), (c) issuer is correct (iss claim), (d) audience matches (aud claim). Never trust a JWT without signature verification.

URLP tools are designed as web-based utilities, not embeddable components or APIs. However, all encoding/decoding functions use standard algorithms you can implement yourself. See our code examples in 7 programming languages on each tool page. For JavaScript-based applications, you can use the same browser APIs our tools use: btoa/atob for Base64, encodeURIComponent/decodeURIComponent for URLs, JSON.stringify/JSON.parse for JSON, etc. For other languages, use the standard library functions shown in our examples. You're welcome to reference our implementations, but please don't iframe or scrape our pages.

URLP tools work with text input only. To encode binary files (images, PDFs, executables), you have several options: (1) Use command-line: base64 input.png > output.txt (Linux/Mac) or certutil -encode input.pdf output.txt (Windows). (2) Use programming languages: PHP: base64_encode(file_get_contents("file.pdf")), Python: base64.b64encode(open("file.bin", "rb").read()), Node.js: fs.readFileSync("file.dat").toString("base64"). (3) For small files (<1MB), some online tools accept file uploads, but remember uploaded data leaves your device. For maximum privacy with sensitive files, use local command-line or programming language solutions.

Client-side (browser-based, like URLP) is faster for small to medium data (up to ~10MB) because there's no network latency. Encoding happens instantly on your CPU. Server-side is better for very large data (100MB+) because servers typically have more RAM and CPU power. Client-side also avoids upload/download time. A 50MB file takes seconds to upload but encodes instantly in your browser. For privacy-sensitive data, client-side is always preferred since data never leaves your device. For automated workflows and very large files, server-side or command-line tools are more appropriate.

JWT tokens include an exp (expiration) claim containing a Unix timestamp (seconds since 1970-01-01). Use our JWT Decoder to inspect the exp value. To check if expired, compare the exp timestamp to current time. In JavaScript: if (decoded.exp * 1000 < Date.now()) { /* expired */ }. Most JWT libraries have built-in expiration checking. They'll throw an error when verifying an expired token. For security: (1) Always check expiration server-side during verification. (2) Use short expiration times (15-60 minutes for access tokens). (3) Implement refresh tokens for long-term access. (4) Never extend expiration by modifying the exp claim. That breaks the signature.

Cross-Site Scripting (XSS) occurs when untrusted user input is displayed on a webpage without encoding, allowing malicious users to inject JavaScript code. Example: if you display <script>alert("hacked")</script> from user input without encoding, the script executes. HTML entity encoding converts < to &lt; and > to &gt;, rendering the script as harmless text: &lt;script&gt;alert("hacked")&lt;/script&gt;. Always encode user input before displaying it in HTML. Use context-appropriate encoding: HTML encoding for content, JavaScript encoding for JS strings, URL encoding for href attributes. Never trust client-side encoding alone. Always encode server-side before rendering. Follow OWASP guidelines for comprehensive XSS prevention.

URLP doesn't provide a public API, but you can automate encoding/decoding in your scripts using standard library functions. See our code examples on each tool page for details. For automation: (1) Python: use base64, urllib.parse, html, json modules. (2) JavaScript/Node.js: use Buffer, encodeURIComponent, JSON, he libraries. (3) Bash: use base64, jq, urlencode commands. (4) PHP: use base64_encode/decode, urlencode, htmlspecialchars, json_encode. These native functions are faster and more reliable than web scraping. For batch processing, write simple scripts rather than relying on web tools.

There's no hard character limit enforced by URLP. The limit is your browser's JavaScript memory. Typical browsers can handle: (1) Text inputs up to 10-50MB without issues. (2) Large JSON files up to 100MB if your device has sufficient RAM. (3) Very large Base64 strings (50MB+) may work but could cause slowdowns. If you hit memory limits, your browser will slow down or display "page unresponsive" warnings. For massive data, use command-line tools (base64, jq) or programming language scripts instead of browser-based tools. For 99% of developer use cases (API responses, config files, JWT tokens), URLP handles inputs instantly.