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Free webmaster tools for SEO and DNS

These free webmaster tools put everything you reach for while running a website in one place. Check a page the way Google and Baidu read it, see why a site is down, look up DNS, WHOIS and certificates, test SPF, DKIM and DMARC, generate robots.txt, sitemaps and structured data, and run or debug Python, C and C++ code. Lookups run live on our server and don't use your daily tasks; formatters, encoders, generators and the programmer tools run in your browser.

SEO ToolsWebsite CheckerDomain & DNS ToolsIP & Network ToolsEmail Deliverability ToolsWebmaster GeneratorsProgrammer ToolsCode Formatter & MinifierEncoding & Encryption

SEO Tools

Check titles, meta tags, links, robots.txt and sitemaps the way search engines read them.

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SEO Broken Link CheckerCheck every link on a page and list the ones that are broken or redirected.
SEO SEO CheckerCheck a page on 40+ on-page and technical SEO points, with a fix for each problem.
SEO Indexability CheckerFind out whether a page can be indexed: status, robots, noindex and canonical in one check.
SEO Keyword Density CheckerSee which words and phrases a page repeats most, and how often.
SEO Meta Tag CheckerRead a page’s title, description, robots, canonical and social tags, with length checks.
SEO Robots.txt TesterRead a site’s robots.txt and test whether a URL is allowed for each crawler.
SEO Search Engine Spider SimulatorSee a page the way Baiduspider or Googlebot does, and whether it differs from what visitors get.
SEO AI Crawler CheckerSee which AI crawlers (GPTBot, ClaudeBot, Google-Extended…) your robots.txt lets in.
SEO Verify Googlebot and Baiduspider IPsCheck whether an IP in your logs really belongs to Google, Baidu or Bing.
SEO Heading Tags Checker (H1–H6)Show a page’s heading outline and flag missing, repeated or skipped levels.
SEO IndexNow URL SubmitterTell Bing, Yandex and other IndexNow engines about new or changed pages.
SEO Link AnalyzerList a page’s internal and external links, nofollow and anchor text, ready to export.
SEO Open Graph CheckerPreview the card a link shows on WeChat, Facebook, X and LinkedIn, and what’s missing.
SEO SERP Snippet PreviewPreview how your title and description show up in Google, Bing and Baidu.
SEO Sitemap CheckerValidate an XML sitemap or sitemap index and spot-check the URLs in it.
SEO Structured Data CheckerExtract JSON-LD and microdata from a page and check common types for missing fields.
SEO AI Title and Description WriterSoonWrite a page title, description and keywords from your page or topic.
SEO Image Alt Text CheckerFind images with missing, empty or unhelpful alt text.

Website Checker

Status codes, redirects, SSL, speed, security headers and what a site is built with.

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WEB Website Speed TestTime DNS, connection, first byte and download for a page, and see what slows it down.
SSL SSL Certificate CheckerCheck a site’s certificate: issuer, expiry, domains covered and whether browsers trust it.
HTTP HTTP Status Code CheckerCheck the status code of one URL or a whole list at once.
HTTP Redirect CheckerFollow every redirect hop, with status codes and timing, and catch loops.
WEB Website Technology DetectorSee the CMS, frameworks, analytics, CDN and server a website uses.
WEB Is It Down?Find out whether a site is down for everyone, and which step fails.
WEB CDN CheckerFind out whether a domain is behind a CDN, and which one.
WEB GZIP and Brotli CheckerCheck whether a page is sent compressed and how much it saves.
WEB Hacked Website CheckerLook for spam redirects, hidden links and content shown only to search engines.
HTTP HTTP Header CheckerSee a URL’s response headers, each one explained.
WEB Mobile-Friendly TestSoonSee how a page looks on a phone and what makes it hard to use.
SSL Security Headers CheckerGrade a site’s security headers (CSP, HSTS, X-Frame-Options…) and see what to add.
WEB View Page SourceRead a page’s HTML with colors, line numbers and search, even on a phone.
WEB Website ScreenshotSoonCapture a full-page screenshot of any website on desktop or phone.
SSL Mixed Content CheckerFind http:// images, scripts and styles that break the padlock on an HTTPS page.

Domain & DNS Tools

WHOIS, domain availability, DNS records, propagation and subdomains.

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DNS DNS LookupLook up A, AAAA, CNAME, MX, NS, TXT, SOA, CAA and other DNS records.
WHOIS WHOIS LookupSee who registered a domain, when it was created and when it expires.
DNS DNS Propagation CheckerAsk a dozen public DNS resolvers at once to see whether a change has spread.
WHOIS Domain Availability CheckerCheck whether domains are still free to register, one or many at once.
DNS Subdomain FinderList a domain’s subdomains from public certificate transparency logs.
DNS DNSSEC CheckerCheck whether a domain is signed with DNSSEC and validates correctly.
xnURL Punycode ConverterConvert Chinese and other international domain names to and from Punycode.
DNS Reverse DNS LookupFind the hostname behind an IP address from its PTR record.

IP & Network Tools

Your IP, IP WHOIS, ping, open ports, subnets and user agents.

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IP IP Location LookupSoonFind the country, region, city and network of an IP address.
IP Ping TestMeasure how fast our server can connect to a host, several times in a row.
IP What Is My IPSee the public IP address websites see, plus your browser and system details.
IP IP WHOIS LookupSee which organization owns an IP address, its network range and ASN.
IP Open Port CheckerCheck whether common ports on your server are open to the internet.
IP IP Subnet CalculatorNetwork, host range and mask for IPv4 and IPv6, plus the broadcast address for IPv4.
IP User Agent ParserTurn a user agent string into browser, engine, system and device.
IP ASN LookupLook up an autonomous system number: its owner, country and registry.
IP IP Address ConverterConvert IP addresses between dotted, decimal, hex and binary, and expand IPv6.
v6IP IPv6 Support CheckerCheck whether a website has IPv6 addresses and answers over IPv6.
MAC MAC Address Vendor LookupSoonFind the manufacturer of a network device from its MAC address.

Email Deliverability Tools

MX, SPF, DKIM and DMARC checks, header analysis and record generators.

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MAIL MX Record LookupSee which mail servers receive email for a domain, in priority order.
MAIL DMARC CheckerRead a domain’s DMARC policy and where its reports go.
MAIL Email Header AnalyzerPaste email headers to see the servers a message passed, delays and SPF/DKIM results.
MAIL Email Address CheckerCheck email addresses for typos, disposable domains and working mail servers.
MAIL SPF Record CheckerCheck an SPF record, expand its includes and count DNS lookups.
MAIL DKIM CheckerFind and check a domain’s DKIM keys, trying common selectors for you.
MAIL DMARC Record GeneratorCreate a DMARC record step by step, from monitoring to reject.
MAIL SPF Record GeneratorBuild a correct SPF record for your mail providers.

Webmaster Generators

Robots.txt, meta tags, schema, sitemaps, redirects and more, generated for you.

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XML XML Sitemap GeneratorCrawl your site or paste a list of URLs to build an XML sitemap.
HTML Meta Tag GeneratorWrite title, description and robots tags with live length checks and a preview.
TXT Robots.txt GeneratorCreate a robots.txt with presets for search engines and AI crawlers.
JSON Schema Markup GeneratorGenerate JSON-LD for FAQ, articles, products, organizations and more.
HTML Open Graph GeneratorMake Open Graph and Twitter Card tags and preview the share card.
CONF 301 Redirect GeneratorGet redirect rules for Apache, Nginx, IIS, PHP and HTML.
URL UTM Link BuilderAdd UTM tags to links so you can track campaigns in analytics.
HTML Hreflang Tag GeneratorBuild hreflang tags for every language version of a page.
CONF Htpasswd GeneratorCreate .htpasswd lines for Apache and Nginx basic authentication.
TXT llms.txt GeneratorWrite an llms.txt that tells AI assistants what your site is about.

Programmer Tools

Run Python, C and C++ in your browser, debug line by line, try HTML, CSS and JavaScript, and turn HTML into text.

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C Online C CompilerCompile and run C with Clang in your browser: typed input, files, and checks that point at the line of a bug.
CPP Online C++ CompilerCompile and run C++11 to C++23 with Clang in your browser, with the standard library and <bits/stdc++.h>.
PY Online Python CompilerWrite and run Python 3.14 in your browser: typed input, files, turtle drawings and matplotlib charts, errors explained.
HTML HTML, CSS & JS Online EditorWrite HTML, CSS and JavaScript and see the page live, with a console, phone and tablet sizes and common libraries.
HTML HTML to Text ConverterTurn HTML into clean plain text, Markdown or CSV: keep the article only, list the links, convert tables, many files at once.
GDB Online Debugger (C, C++, Python)Step through C, C++ or Python line by line, backwards too: breakpoints, variables, watches, the call stack and GDB-style commands.

Code Formatter & Minifier

Format and minify HTML, CSS, JavaScript, SQL and XML right in your browser.

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HTML HTML FormatterIndent messy HTML so it’s easy to read.
JS JavaScript FormatterBeautify minified or messy JavaScript.
HEX Color ConverterConvert colors between HEX, RGB, HSL and CMYK, and check contrast.
CRON Cron Expression GeneratorBuild cron expressions and see the next run times in plain words.
CSS CSS FormatterTurn minified CSS into neat, readable rules.
CSS CSS MinifierMinify CSS to load faster.
HTML HTML MinifierShrink HTML by removing comments and extra whitespace.
HTTP HTTP Request TesterSend GET, POST and other requests to a public API and read the response.
JS JavaScript MinifierStrip comments and whitespace from JavaScript without changing how it runs.
JSON JSON to CodeTurn JSON into TypeScript, Java, Go, Python, C# or PHP classes.
SQL SQL FormatterFormat SQL queries with clean line breaks and indentation.
XML XML FormatterFormat and validate XML, with errors pointed out.
CSS CSS Gradient GeneratorDesign linear and radial gradients and copy the CSS.
CURL cURL to Code ConverterConvert cURL commands to Python, JavaScript, PHP, Go and more.

Encoding & Encryption

Unicode, timestamps, number bases, hashes, AES, RSA and JWT, all on your device.

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HASH Hash GeneratorGet MD5, SHA-1, SHA-256, SHA-512 and SM3 hashes of text in one go.
TIME Unix Timestamp ConverterConvert Unix timestamps to dates and back, in your time zone and UTC.
U+UNI Unicode ConverterConvert text to and from \u escapes, &#; codes, U+ points and UTF-8 bytes.
AES AES Encrypt and DecryptEncrypt or decrypt text with AES in GCM, CBC or CTR mode.
&;HTML HTML Entity Encoder/DecoderEscape text into HTML entities, or turn entities back into text.
JWT JWT DecoderDecode a JSON Web Token’s header and payload and check its expiry and signature.
01BIN Number Base ConverterConvert numbers between binary, octal, decimal, hex and any base up to 36.
BASE Base32 and Base58 EncoderEncode and decode Base32, Base58, Base85 and Base16.
0xHEX Text to Hex ConverterTurn text into hexadecimal bytes in UTF-8, GBK or UTF-16, and back.
HMAC HMAC GeneratorSign a message with a secret key using HMAC-SHA256 and other hashes.
·–MORSE Morse Code TranslatorTranslate text to Morse code and back, and play it as sound.
PWD Password Strength CheckerSee how hard a password is to guess and how to make it stronger.
RSA RSA Key Generator and EncryptionGenerate RSA key pairs, encrypt, decrypt, sign and verify.
FAQ

Webmaster Tools: questions and answers

Are the webmaster tools free?
Yes, and you don't need an account. Lookups such as DNS, WHOIS, SSL and SEO checks don't use your daily tasks; there's an hourly allowance to stop abuse, larger for members and VIP. Only the sitemap crawler counts as a task.
Do you store the sites or domains I check?
No. A check runs when you click and the result is shown to you only. Tools marked "runs in your browser" never send what you type anywhere.
Can you show Baidu weight, rankings or backlinks?
No. Those numbers come from scraping search engines at scale, which breaks their terms. Instead, the Indexability Checker tells you whether a page can be indexed, with links to site: searches and the official webmaster platforms.
Why does a check from your server differ from what I see?
We test from our server's network. Speed, DNS answers from nearby resolvers and CDN routing can differ in your city or on your ISP. The DNS Propagation Checker asks public resolvers in several countries to show that spread.