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Free Website, SSL, DNS & SEO Tools

Check any website's SSL, DNS, domain, security headers, email setup, speed and SEO in seconds - free, instant and with no signup.

120 free tools 10 categories No signup Works on mobile

Matching tools

No tool matches that search. Try a shorter word such as "SSL", "DNS" or "SEO", or browse the categories below.

See all 120 tools
Website Trust Checker Check if a website looks legit or risky - a free trust score from doma...
Website Status Checker Find out instantly whether a website is up for everyone or only failin...
SSL Certificate Checker See whether a website's HTTPS certificate is valid, trusted by browser...
DNS Lookup Pull up all of a domain's main DNS records in one view - where the web...
WHOIS / RDAP Lookup See a domain's public registration record - registrar, key dates, stat...
Domain Availability Checker Check whether a domain name is free to register or already taken.
Redirect Checker Follow a URL through every redirect to see each hop, its status code a...
Security Headers Checker Grade a website's HTTP security headers and see which protections are...

Browse by category

SSL Tools

Check and monitor SSL/TLS certificates.

3 tools

DNS Tools

Look up and inspect DNS records.

13 tools

Domain Tools

Domain registration, expiry, and ownership tools.

13 tools

Website Tools

Check the status and health of any website.

24 tools

Security Tools

Scan for common website security issues.

15 tools

Email Tools

Email deliverability and configuration tools.

10 tools

Performance Tools

Measure and monitor website performance.

12 tools

SEO Tools

Lightweight on-page SEO analysis for any URL.

14 tools

Web Server Tools

Nginx, Apache .htaccess, cron and file-permission generators for running your ow...

7 tools

Website Image Tools

Compress, resize and convert images so your pages load fast.

9 tools

All free tools

Website Tools

Run All Checks

Check the status and health of any website.

Website Status Checker Find out instantly whether a website is up for everyone or only failing for you.
HTTP Status Checker See the HTTP status code a page returns, from 200 OK to 404 and 5xx errors.
IP Address Lookup Find the IP address of the server a website runs on, with its reverse DNS name.
HTTP Headers Checker See every HTTP response header a website sends back to browsers.
Redirect Checker Follow a URL through every redirect to see each hop, its status code and the final page.
Website Response Time Checker Measure how quickly a website's server answers a request.
Robots.txt Checker Fetch a website's robots.txt and read the crawling rules it gives to search engines.
Sitemap Checker Check whether a website has an XML sitemap that search engines can find and read.
Favicon Checker Check whether a website's favicon is declared correctly and actually loads.
Website Technology Checker Discover the CMS, frameworks, analytics and server software behind any website.
HTML Validator Scan a live page's HTML for structural errors, missing tags and accessibility issues.
CSS Validator Check the stylesheets a page uses for CSS syntax errors.
JSON Formatter Instantly format and pretty-print any JSON, right in your browser.
JSON Validator Instantly check whether your JSON is valid, right in your browser.
JSON Minifier Instantly minify JSON by removing whitespace, right in your browser.
URL Encoder / Decoder Instantly encode or decode URLs and query strings, right in your browser.
Base64 Encoder / Decoder Instantly encode or decode Base64 text, right in your browser.
Unix Timestamp Converter Instantly convert Unix timestamps to human-readable dates, and back, right in your browser...
Broken Link Checker Scan a page for links that lead to missing or failing pages.
Website Charset Checker Check the character encoding a page declares in its headers and HTML.
HTML Minifier Instantly minify HTML by removing unnecessary whitespace and comments, right in your brows...
JavaScript Minifier Instantly compact JavaScript by removing unnecessary whitespace, right in your browser.
URL Parser Instantly break a URL down into its protocol, host, path, query parameters, and fragment,...
Who Is Hosting This Website Find out which company hosts a website, plus who runs its DNS and email - from the server...

Security Tools

Run All Checks

Scan for common website security issues.

Security Headers Checker Grade a website's HTTP security headers and see which protections are missing.
HTTPS Redirect Checker Check that visitors who type http:// are sent to the secure https:// version of a site.
HSTS Checker Check whether a site tells browsers to always use HTTPS with the HSTS header.
Website Trust Checker Check if a website looks legit or risky - a free trust score from domain age, SSL, HTTPS,...
Content Security Policy (CSP) Checker Check whether a site uses a Content-Security-Policy and see the rules it sets.
X-Frame-Options Checker Check whether a site stops other websites from loading it inside a frame.
X-Content-Type-Options Checker Check whether a site tells browsers not to guess file types (nosniff).
Referrer-Policy Checker Check how much of a page's address a site shares with other websites through the Referer h...
Permissions-Policy Checker Check which browser features a site allows itself and embedded content to use.
CORS Header Checker Check which other websites a site or API allows to read its responses (CORS).
Mixed Content Detector Check whether an HTTPS site guards against insecure http:// resources breaking its padlock...
JWT Decoder Instantly decode a JWT's header and payload, right in your browser.
SHA-256 Hash Generator Instantly generate a SHA-256 hash of any text, right in your browser.
MD5 Hash Generator Instantly generate an MD5 hash of any text, right in your browser.
Password Strength Checker Instantly check how strong a password is, right in your browser - never sent anywhere.
Why JustChecker

Free tools for the everyday work of running a website

JustChecker is a growing collection of free online tools for website owners, developers and anyone who looks after a site. Each one does a single job well, opens straight away and needs no account.

  • Instant results, no signup
  • Developer tools run in your browser - pasted data stays on your device
  • Works the same on desktop and mobile
  • Every tool explains its result and how to fix what it finds
Read the Guides

For website owners

Check that your SSL certificate is valid and not about to expire, look up DNS records after a hosting move, make sure email passes SPF, DKIM and DMARC, and review security headers, page speed and on-page SEO against the live site.

SSL certificates DNS records SPF, DKIM & DMARC Security headers Page speed On-page SEO Domains & WHOIS

For developers

Format and validate JSON, decode JWTs, encode Base64 and URLs, generate hashes, minify HTML and JavaScript, convert Unix timestamps and inspect HTTP headers - without installing anything.

JSON formatter JWT decoder Base64 URL encoder SHA-256 / MD5 HTML & JS minifier Unix timestamps HTTP headers

Looking for something else?

Search or browse every tool, grouped by what it helps you do.

Explore All Tools Browse Categories

Frequently asked questions

Yes. Every tool on this page is free to use with no account, no trial and no usage fee. JustChecker is funded by its website monitoring plans, not by charging for these checks.

No. Open a tool, enter a domain or paste your data, and you get the result straight away in your browser. Nothing needs to be installed.

No. The JSON, Base64, URL, JWT, hash, minifier, timestamp, Punycode and password tools run entirely in your browser - what you paste stays on your device. Only domain-based checks (such as SSL, DNS or HTTP checks) query the domain from our servers.

Domain-based tools query live DNS, WHOIS/RDAP and the website itself at the moment you run them, so results reflect the current state. Some results are cached for a short time; use Refresh Result on a tool page to run a fresh check.

Yes. Use Run All Checks next to a category to run every tool in it against one domain and get a combined report you can download as PDF or JSON.

The free tools check a site once, when you ask. To be alerted automatically when a website goes down or a certificate or domain is about to expire, add the site to JustChecker website monitoring.