What makes a URL valid?

A valid web URL must have a protocol (https:// or http://), a hostname (a domain name or IP address), and no illegal characters. The path, query string, and fragment are optional but must follow standard encoding rules if present.

Why does my URL show 'missing protocol'?

If you typed something like 'example.com' without a protocol prefix, the tool flags it because a bare domain is not a complete URL. Browsers need the scheme (https:// or http://) to know how to connect to the server. Adding https:// at the start fixes this.

What is the difference between http:// and https://?

Both are valid web protocols, but https:// encrypts the connection between the browser and the server using TLS. http:// sends data in plain text, which means anyone on the same network could intercept it. For any live website, https:// is the correct choice.

Why are spaces not allowed in URLs?

The URL specification (RFC 3986) defines URLs as sequences of ASCII characters with no whitespace. Spaces break the URL structure and must be encoded as %20 in paths or + in query strings before being included in a URL.

What is a valid port number?

Port numbers must be integers between 0 and 65535. The standard port for HTTPS is 443 and for HTTP it is 80 — browsers use these automatically, so you can omit the port for most URLs. A value like 99999 is out of range and makes the URL invalid.

What are URL components?

A URL can contain up to six components: Protocol (the scheme, e.g. https://), Host (the domain or IP), Port (optional network port), Path (the resource location on the server), Query string (key-value parameters after ?), and Fragment (an in-page anchor after #).

Is my URL stored or sent anywhere?

No. All validation happens entirely in your browser using JavaScript. Your URL is never sent to any server and is never stored or logged.

Does the tool check whether the URL is reachable?

No — this tool validates URL structure and syntax only. It does not make any network requests or check whether the page at the URL actually exists or returns a response. Use a link checker or HTTP status tool for reachability testing.

🔗URL Checker·Free online tool

URL Checker

Paste any URL to instantly check whether it is valid. Get specific, plain-English error messages for every possible issue — missing protocol, illegal characters, invalid port, unsupported scheme — plus real-time hints as you type and a colour-coded visual breakdown of every URL component.

Guide

How to Use This Tool

1
Paste or type your URL
Enter any URL into the input field. The tool begins analysing it character by character as soon as you start typing — no submit button needed.
2
Read the real-time hints
As you type, contextual hints appear below the input. These surface issues like an unencrypted http:// scheme, a single-label hostname, or misplaced query and fragment components — before you even finish typing.
3
Check the validation result
Once you pause or complete the URL, the tool shows either a green Valid banner or a red error card. Errors include a plain-English explanation of what is wrong and a specific suggestion for how to fix it.
4
Apply the suggested fix
If the tool can automatically correct the URL — for example by adding the missing https:// or encoding spaces — a suggested fix appears with a 'Use this →' button. Click it to load the corrected URL directly into the input.
5
Explore the URL breakdown
When the URL is valid, a colour-coded breakdown appears showing every component — Protocol, Host, Port, Path, Query, Fragment — each with a description of what it does and how it affects the request.

Examples

See It in Action

The URL Checker handles every class of URL error. Here are the four most common cases and what the tool reports for each.

Valid URL — full breakdown

Input

https://www.example.com/blog?page=2#comments

Output

Protocol: https:// · Host: www.example.com · Path: /blog · Query: ?page=2 · Fragment: #comments

Missing protocol

Input

www.google.com

Output

Error: Missing protocol (scheme) → Suggested fix: https://www.google.com

Space in URL

Input

https://example.com/my page

Output

Error: Spaces are not allowed in URLs → Suggested fix: https://example.com/my%20page

Invalid port

Input

https://example.com:99999/

Output

Error: Invalid port number: 99999 → Suggested fix: https://example.com/

About

About the URL Checker Tool

The URL Checker validates any web address against the URL specification and tells you exactly what is wrong — in plain English — if anything fails. All processing runs in your browser with zero network requests.

What Is a URL?

A URL (Uniform Resource Locator) is a structured string that uniquely identifies a resource on the web. It encodes where a resource lives (the host), how to reach it (the protocol), and which specific resource to return (the path, query, and fragment). Every component has strict syntax rules — a single error anywhere in the string makes the entire URL unusable.

Why URL Validation Matters

Malformed URLs silently break links, fail API calls, and cause 404s that are hard to trace. Developers use URL validation when building forms, parsing user input, or debugging integrations. Content teams use it to verify links before publishing. QA engineers use it to catch broken redirects before they reach production.

Free foreverNo sign-upWorks offlinePrivacy-firstInstant results

FAQ

Frequently Asked Questions

It parses the URL you enter and determines whether it is structurally valid. If the URL has a problem — missing protocol, illegal characters, out-of-range port, unsupported scheme — the tool explains exactly what is wrong and suggests a corrected version.