Web & SEO

Need to check a URL's structure? Validate a credit card number format? See if your design works at different screen sizes? These web essentials have you covered.

Common Problems

What are the parts of a URL?

How does credit card validation work?

What screen size should I design for?

Tools

URL Parser

Break down URLs into components

Credit Card Validator

Validate card numbers with Luhn algorithm

Screen Resolution

Check screen sizes and pixel densities

JSON Formatter

Format and validate JSON data

Learn More

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Web & SEO Tools Guide

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JSON & Data Formats

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URL Structure Explained

Frequently Asked Questions

What are the parts of a URL?

A URL has: protocol (https://), domain (example.com), port (:443), path (/page), query string (?key=value), and fragment (#section). Our URL parser breaks these down instantly.

How does credit card validation work?

Online validators use the Luhn algorithm — a checksum formula that verifies the card number is valid. It doesn't check if the card is real or has funds, just that the number is mathematically valid.

What screen size should I design for?

Design mobile-first at 375px width, then adapt for tablets (768px) and desktops (1280px+). Common breakpoints: 640px (sm), 768px (md), 1024px (lg), 1280px (xl).