Web Tools
Tools for web developers and SEO (JWT, URLs, DNS, HTTP headers, meta tags, sitemaps)
Decode, create and verify JWTs, parse URLs, look up HTTP status codes, test CORS and CSP settings, and generate meta tags, Open Graph tags, robots.txt, sitemaps, .htaccess rules and structured data. Network tools look up DNS records, IP addresses, WHOIS data and certificates or check the headers and redirects of a live URL; these contact an external service or our own endpoint when you run them, as explained in the Privacy Policy.
Tools in this category: 43
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All tools in this category
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JWT Decoder
Decode a JWT to read its header, payload claims and signature, with exp, nbf and iat shown as dates and an expiry status. Runs locally; nothing is uploaded.
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JWT Verifier
Verify a JSON Web Token's signature with an HMAC secret, PEM public key, X.509 certificate, JWK or JWKS, and check exp, nbf, issuer and audience locally.
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Meta Tag Generator
Generate the HTML head tags for SEO: title, meta description, canonical link, robots noindex/nofollow, viewport, charset and theme-color, with length counters.
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Robots.txt Generator
Create a valid robots.txt: allow or block crawlers, disallow paths with wildcards, add Allow exceptions, Crawl-delay, sitemap URLs and block AI training bots.
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Sitemap Generator
Turn a list of page URLs into a valid sitemap.xml with optional lastmod, changefreq and priority. Removes duplicates, escapes &, flags invalid lines.
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Breadcrumb Generator
Create BreadcrumbList structured data and accessible breadcrumb HTML (nav, ol, aria-current) from a list of page names and URLs. Copy-ready JSON-LD.
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Canonical URL Checker
Check a page's rel="canonical" tag and HTTP Link header, compare it with the final URL and spot missing, multiple or conflicting canonicals and noindex.
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Chmod Calculator
Convert Linux file permissions between octal (755) and symbolic (rwxr-xr-x), including setuid, setgid and sticky bits, and copy the chmod command.
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CIDR to IP Range
Convert a CIDR block to its first and last IP and list every address, or turn an IP range into the minimal set of CIDR blocks. IPv4 and IPv6, in-browser.
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CORS Tester
Send a real cross-origin request from your browser to any API to see if CORS allows it. Explains when a preflight is needed and shows readable headers.
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Credit Card Validator
Check a card number with the Luhn algorithm, detect the network (Visa, Mastercard, Amex, Discover, JCB, UnionPay…) and validate its length. Nothing is sent.
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CSP Generator
Build a Content-Security-Policy directive by directive, export it as header, meta tag, Nginx or Apache config, and get warnings for unsafe settings.
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CSS Selector Tester
Test CSS selectors against pasted HTML and see every matching element with its markup and text. Uses querySelectorAll, so results match the browser exactly.
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DNS Lookup
Query DNS records (A, AAAA, CNAME, MX, TXT, NS, SOA, CAA, SRV, PTR) for any domain over DNS-over-HTTPS, with TTLs, NXDOMAIN status and DNSSEC flag.
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Email Validator
Validate email addresses in bulk against practical RFC 5322 rules, catch typos like gmial.com, and optionally check the domain's MX records over DNS.
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Favicon Checker
Check which favicons a website declares, whether each icon URL and /favicon.ico actually loads (status, type, size), and if apple-touch-icon and manifest exist.
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.htaccess Generator
Generate Apache .htaccess rules: force HTTPS, add or remove www, 301 redirects, error pages, gzip, browser caching, security headers and dotfile blocks.
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HTTP Headers Checker
Fetch any public URL and view its HTTP status and response headers, with checks for HSTS, CSP, X-Frame-Options, nosniff and other security headers.
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HTTP Status Codes
Searchable list of every HTTP status code in the IANA registry (100–511) with reason phrase, defining RFC and a plain explanation of when it is used.
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IBAN Validator
Validate an IBAN with the ISO 13616 mod-97 checksum and the official length for 89 countries. Shows BBAN, print format and the correct check digits.
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IP Address Lookup
Find the approximate location, ISP, organization and ASN of an IPv4 or IPv6 address, or see your own public IP. Private addresses are recognised locally.
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JWT Generator
Create signed JSON Web Tokens with HS256/384/512, RS, PS, ES or EdDSA. Edit the payload, set exp and iat, generate keys or secrets – all in your browser.
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Keyword Ideas Generator
Expand a seed keyword into long-tail ideas with modifiers, questions and comparisons in your language, plus your own modifiers and A–Z variations. CSV export.
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Link Analyzer
List all links on a web page with anchor text, internal/external classification, nofollow, sponsored and ugc attributes, empty anchors and missing noopener.
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MAC Address Lookup
Look up the manufacturer of a MAC address from the IEEE OUI registry (MA-L, MA-M, MA-S), see unicast/multicast and local bits. Lookups happen in your browser.
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Open Graph Generator
Create Open Graph meta tags for Facebook, LinkedIn, WhatsApp, Slack and Discord link previews: title, description, image with size and alt, type, URL, locale.
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Page Speed Checklist
Paste a page's HTML to find render-blocking scripts, images without size or lazy loading, missing viewport, @import, document.write and more.
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Phone Number Validator
Validate phone numbers for any country with Google's libphonenumber data: valid or possible, mobile/landline type, E.164, international and national formats.
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Port Number Lookup
Search common TCP and UDP port numbers by number, range or service name: SSH 22, HTTPS 443, MySQL 3306, PostgreSQL 5432 and more. Shows port category.
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Port Checker
Check whether one TCP port on a public host accepts connections from the internet: open, closed or filtered. One port per check, no mass scanning.
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Redirect Checker
Follow a URL's redirect chain hop by hop: status code (301, 302, 307, 308), Location target and final URL. Detects redirect loops and long chains.
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Schema Markup Generator
Generate schema.org JSON-LD structured data for Article, Organization, Person, Product, FAQPage, Event, LocalBusiness and WebSite from a simple form.
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SERP Preview
See how your title and meta description may look in Google results. Measures pixel width with the canvas API and truncates like Google at about 600 px.
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Social Media Preview
Preview how a link may look when shared on Facebook, X and LinkedIn from its title, description and image, or load the og: tags straight from a page URL.
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SSL Certificate Checker
Test that a site's HTTPS connection succeeds and see its newest certificate from Certificate Transparency logs: issuer, validity, days left, names.
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Subnet Calculator
Calculate network, broadcast, wildcard mask, first/last host and usable hosts for any IPv4 or IPv6 subnet. Accepts CIDR or dotted netmask, runs in your browser.
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Twitter Card Generator
Generate twitter:card meta tags for X (Twitter) link previews: summary or summary_large_image, site and creator handles, title, description, image and alt.
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URL Parser
Break any URL into scheme, credentials, host, port, path segments, query parameters and fragment, with decoded values and JSON output. Runs in your browser.
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URL Query Builder
Build a URL with query parameters from key/value pairs, using form encoding (space as +) or RFC 3986 (%20). Import parameters from an existing URL.
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URL Validator
Validate one or many URLs with the same parser browsers use. Flags missing schemes, spaces, invalid hosts, credentials, plain http and shows the normalized URL.
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User Agent Parser
Parse any User-Agent string into browser, engine, operating system, device type, vendor/model and CPU, and detect search and AI crawlers. Runs locally.
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WHOIS Lookup
Look up domain registration data via RDAP: registrar, creation and expiry dates, status codes, name servers and DNSSEC. Also works for IP networks and ASNs.
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XPath Tester
Test XPath 1.0 expressions against XML or HTML and see matching nodes, attributes, text and numeric or string results instantly, using the browser's engine.
Other categories
- CRC Cyclic Redundancy Check algorithms for error detection
- MD Message Digest algorithms (MD2, MD4, MD5)
- SHA-1 Secure Hash Algorithm 1 - 160-bit hash function
- SHA-2 Secure Hash Algorithm 2 family (SHA-224, SHA-256, SHA-384, SHA-512)
- SHA-3 Secure Hash Algorithm 3 based on Keccak
- Keccak Keccak cryptographic hash function
- SHAKE Extendable-output functions (SHAKE128, SHAKE256)
- cSHAKE Customizable SHAKE functions
- KMAC Keccak Message Authentication Code
- Password & Security Password generation, analysis, hashing, and security tools
- Encryption & Cryptography Symmetric and asymmetric encryption, HMAC and key generation (AES, 3DES, RSA, PGP)
- Encoding Encode and decode data: Base64, Base32, Base58, URL, HTML entities, hex, Unicode and more
- Formatters Format, minify and validate code and data (JSON, XML, YAML, SQL, HTML, CSS) and convert naming cases
- Generators Generate IDs, keys, test data, QR codes, barcodes and config files (UUID, API keys, .gitignore, Dockerfile)
- Converters Convert data formats, number bases, colours, timestamps, units and currencies (JSON, CSV, YAML, XML)
- Text Tools Count, compare, clean and transform text (word count, diff, regex, case, duplicates)
- Image Tools Tools for manipulating and converting images (Compress, Resize, Convert)
- Design & CSS Generate CSS visually: shadows, gradients, flexbox and grid layouts, animations and colour palettes
- Math & Calculators Calculators for finance, health, percentages, programmer arithmetic and everyday maths
- Time & Date Time zones, date differences, business days, timers, stopwatch and world clock