Web Tools

Utilities for DNS, email records, HTTP headers, URLs, CSS, and SEO checks.

Explore 25 free web tools, including Cache-Control Header Builder, Color Contrast Checker, Color Converter, CSS Box Shadow Generator, and more.

Choose the right tool

Web troubleshooting often crosses several layers: a URL identifies a resource, HTTP headers describe a response, DNS directs traffic, and crawler instructions affect discovery. Select the layer that matches the symptom. Pasted configuration can be checked for structure, but a syntactically valid record or header does not prove that it is deployed or that every client interprets it as intended.

URL Parser & Inspector: Separate a URL's host, path, query, and fragment before investigating routing.
HTTP Header Parser: Inspect copied response headers and distinguish them from the response body.
Robots.txt Tester: Test crawler rules for a path; robots.txt is not an access-control mechanism.
Color Contrast Checker: Evaluate text and background contrast before using a colour pair in an interface.

Page 1 of 2. Showing 24 of 25 tools.

Cache-Control Header Builder

Build and understand HTTP Cache-Control directives.

Color Contrast Checker

Check WCAG text contrast ratios for two web colors.

Color Converter

Convert and preview HEX, RGB, and HSL colors.

CSS Box Shadow Generator

Build layered CSS box shadows with a live preview.

CSS Clamp Calculator

Build fluid CSS clamp() values from size and viewport endpoints.

CSS Gradient Generator

Create copyable linear and radial CSS gradients with a live preview.

CSS Specificity Calculator

Compare CSS selector specificity scores.

CSS Text Shadow Generator

Build layered CSS text shadows with a live preview.

CSS Unit Converter

Convert relative CSS units with the context that determines their real size.

DKIM Record Generator

Build a DKIM TXT record for email signing.

DMARC Record Generator

Build a DMARC TXT record for domain email protection.

DNS Record Validator

Check DNS record values before adding them to a provider.

Email Header Analyzer

Inspect SPF, DKIM, DMARC, and delivery path headers.

Heading Hierarchy Checker

Inspect an HTML heading outline and spot skipped levels.

HTML Entity Encoder / Decoder

Convert text to and from HTML entities directly in your browser.

HTTP Header Parser

Parse and inspect raw HTTP header fields locally.

HTTP Status Code Lookup

Find HTTP status meanings and next steps.

Meta Tag Previewer

Preview search and social snippets from page metadata.

Query String Builder

Build encoded URL query strings from key-value parameters.

Robots.txt Tester

Check robots.txt rules for a crawler and path.

Slug Generator & Checker

Create URL-safe slugs and check duplicate page paths.

SPF Record Generator

Build an SPF TXT record for domain email senders.

URL Encode / Decode

Convert URL text to and from percent encoding.

URL Parser & Inspector

Inspect URL components and query parameters.

Worked example: inspect a campaign link

For https://example.com/guide?utm_source=newsletter#examples, the host is example.com, the path is /guide, and utm_source is a query parameter.
The #examples fragment points to a location in the page and is not sent as part of the HTTP request. Check that the target page actually contains the matching anchor.
When building a tagged link, keep the destination path intact and encode parameter values once. Open the finished link and confirm that it lands on the intended content before sharing it.

Common mistakes to avoid

A robots.txt disallow rule can prevent crawling without preventing a URL from appearing in search. It also does not protect private content.
A search snippet preview is illustrative. Search engines can rewrite titles and descriptions; DNS changes also need live verification after deployment.