Validators & Checkers
Free, private validators and format checkers — VAT and tax IDs, IBAN and bank codes, national identity numbers, VIN, accessibility (WCAG), data formats and more. Every check runs entirely in your browser; nothing you enter is uploaded or stored.
Instantly check whether a number or value is structurally valid: VAT numbers and tax IDs by country, IBANs (MOD97), national identity numbers (CPF, Aadhaar, NINO and dozens more), VINs, postal codes, phone formats, and accessibility/data-format rules. Each validator applies the official structure and check-digit algorithm, so you catch typos and bad data before they cause problems.
All validation happens client-side in your browser — the value you paste is never transmitted to a server, stored, or logged. That makes these tools safe for sensitive identifiers like tax, bank and ID numbers.
All
Palette Colour-Blindness Safe Checker
Paste a palette and see which colour pairs become indistinguishable across 8 colour-vision-deficiency types.
Accessible Name Computer
Paste an interactive element and compute the name a screen reader will announce
Age Verification & Date-of-Birth Calculator
Calculate exact age from a DOB and verify against jurisdiction-specific age thresholds
Alt Text Length & Quality Checker
Paste HTML and flag images with missing, empty, or oversized alt attributes
Animation Frame-Rate & Flash Risk Estimator
Paste a CSS keyframe animation and estimate flash frequency for seizure safety
ARIA Live Region Debugger
Paste HTML and validate aria-live, aria-atomic and aria-relevant on dynamic regions
ARIA Role Reference & Attribute Validator
Look up any WAI-ARIA role and validate required/permitted attributes locally
autocomplete Attribute Validator
Paste a form and verify input autocomplete values are valid WCAG 1.3.5 tokens
Colour Contrast Live Preview
Type two hex codes and see a live text + button preview alongside the WCAG contrast ratio.
Gradient Text Accessibility Checker
Analyse contrast across a CSS gradient background to find failing text regions
Colour Name to Hex / RGBA Converter
Convert CSS named colours, Tailwind classes, and hex to every colour space
Consent Withdrawal Flow Checker
Assess whether your consent withdrawal is as easy as granting it (GDPR Art. 7.3).
Contrast Matrix Generator
Paste a palette and get an NxN WCAG contrast-ratio grid for every colour pair
Dark Mode Contrast Tester
Check that your colour pairs meet WCAG in both light and dark themes simultaneously
Data Retention Period Calculator
Calculate the earliest lawful deletion date for any data category under GDPR and more
Diceware Passphrase Generator
Generate cryptographically random passphrases from a word list, fully offline
File Metadata Scrubber
Strip author, company, and revision data from DOCX, XLSX, and PPTX files
Focus-Indicator Contrast Checker
Verify your CSS focus ring meets the WCAG 2.2 SC 1.4.11 minimum 3:1 contrast.
Font Size to rem Accessibility Converter
Convert px to rem and verify text scales with browser zoom to WCAG 1.4.4
Form Label & Accessible-Name Checker
Paste a form and detect every input, select or textarea missing an associated label or accessible name.
GDPR 72-Hour Breach Notification Countdown Timer
Start the GDPR 72-hour ICO notification clock from the moment of discovery
Local File Hash Generator (SHA-256/SHA-1/MD5)
Drop any file and compute its SHA-256, SHA-1, and MD5 checksums entirely in-browser
Heading Order Checker
Paste HTML and visualise the heading hierarchy with skipped-level warnings.
Have I Been Pwned — k-Anonymity Breach Checker
Check if your password appeared in a data breach using only a hash prefix
Icon-Only Button Accessible-Name Checker
Paste HTML to detect icon-only buttons missing an accessible name
Images-of-Text Detector
Paste HTML and flag img and background-image elements that likely encode text under WCAG 1.4.5.
Security Incident Severity Calculator
Score a security incident across impact, exploitability, and urgency for triage
lang Attribute Checker
Validate that HTML documents and inline elements have correct BCP 47 lang values
Large Text Contrast Checker
Verify contrast for 18pt+ and 14pt-bold text using relaxed WCAG thresholds
Link Text Quality Checker
Paste HTML and flag ambiguous link text like click here and read more.
Logical Focus Order Checker
Paste HTML and highlight modals, drawers, and widgets that may trap or lose focus.
Motion & Animation Safety Checker
Paste CSS and flag animations that may trigger vestibular disorders or seizures
Password Strength & Entropy Meter
Calculate real bit-entropy and crack time for any password — fully offline
Phishing URL Heuristic Checker
Score any URL for phishing risk using 15 local heuristics — no cloud lookup
QR Code Safety Inspector
Decode a QR code image and show the embedded URL before you open it
Visual vs DOM Reading-Order Checker
Paste CSS flexbox or grid and flag visual order diverging from DOM order
Reflow Viewport Width Checker
Test whether your content layout works at 320 CSS px width (WCAG 1.4.10)
Required Field Indicator Checker
Verify required form fields are indicated in text, not just colour (WCAG 1.3.3)
Screenshot & Image Metadata Viewer
Read EXIF, IPTC, and XMP metadata from any image without uploading it anywhere
Semantic HTML Auditor
Paste HTML and flag div-soup, missing landmarks, fake buttons and broken heading outlines.
Sensitive File Path Exposure Checker
Paste a list of server paths and flag ones that expose config, backups, or .git
Skip-Link Validator
Paste your HTML and verify that a working skip-to-content link is present, targeted and keyboard-reachable.
SVG Accessibility Checker
Paste inline SVG and verify title, desc, role and aria-labelledby presence
Tab-Order Visualizer
Paste HTML and see the keyboard focus sequence numbered in document order.
Table Header & Scope Checker
Validate that your HTML tables have th elements with correct scope attributes.
TOTP Token Generator (Offline)
Generate time-based OTP codes from a secret key entirely offline in your browser.
Touch-Target Size Checker
Enter width and height in CSS units and check against the 44x44 px WCAG 2.5.5 minimum.
URL Privacy & Fingerprinting Risk Checker
Analyse a URL for embedded identifiers, tracking tokens, and fingerprinting signals
URL Unshortener & Redirect Tracer
Follow every redirect hop for bit.ly, t.co and custom shorteners — no click needed
WAI-ARIA Authoring Practices Pattern Reference
Browse the official ARIA design patterns (dialog, combobox, tabs, etc.) offline
WCAG 2.1 Self-Audit Checklist
Walk through every WCAG 2.1 Level A and AA success criterion with pass/fail tracking saved locally.
WCAG-Accessible Colour Palette Suggestor
Enter a brand colour and get AA-compliant text colours auto-generated
Argentina CUIT/CUIL Validator
Validate Argentine tax and labor identity numbers (CUIT/CUIL)
aria-describedby & aria-details Validator
Paste HTML and verify that all aria-describedby references resolve to real IDs
Australia ABN Validator
Validate Australian Business Numbers with the ABR check algorithm
Australia ACN Validator
Validate Australian Company Numbers with the ASIC check digit
Austria PLZ Validator
Validate an Austrian 4-digit Postleitzahl and map it to its Bundesland
Austria UID Number Validator
Validate Austrian VAT (UID) numbers with the official check rule
Bangladesh e-TIN Validator
Validate Bangladeshi National Board of Revenue e-TIN numbers (12 digits)
Belgium National Register Number Validator
Validate a Belgian rijksregisternummer with the modulo-97 check.
Belgium VAT Number Validator
Validate a Belgian TVA/BTW number (BE + 10 digits) with mod-97.
Brazil CEP Postal Code Validator
Validate Brazilian CEP postal codes format and region
Brazil PIS/PASEP Validator
Validate Brazilian PIS and PASEP worker-identification numbers
Canada Business Number Validator
Validate Canadian 9-digit BN used for GST/HST registration
China Resident ID Card Validator
Validate Chinese 18-digit resident identity card numbers
China Mobile Number Validator
Validate an 11-digit Chinese mobile number and identify its carrier
China Postal Code Validator
Validate Chinese 6-digit postal codes by province prefix
China Unified Social Credit Code Validator
Validate Chinese 18-character USCC with the GB 32100 check character
Colour Temperature & Night-Mode Accessibility Checker
Check whether warm-tinted night-mode colours still meet WCAG contrast
WCAG Contrast Ratio Algorithm Tester
Step through the WCAG 2.x relative luminance formula with full intermediate values shown
CVE CVSS v3.1 Severity Calculator
Score a vulnerability using the full CVSS v3.1 formula and get the severity label.
Czech DIČ (VAT) Validator
Validate a Czech VAT identification number (DIČ) for entities and natural persons.
Czech PSČ Postal Code Validator
Validate a Czech 5-digit PSČ and map its prefix to a postal region
Czech Rodné číslo Validator
Validate a Czech national birth number (rodné číslo) and decode its date and sex.
Denmark CVR Validator
Validate Danish company registration numbers (CVR)
Denmark Postnummer Validator
Validate a Danish 4-digit postnummer and map it to its region
Denmark VAT Number Validator
Validate Danish momsregistreringsnummer (DK prefix + 8-digit CVR)
Ethiopia TIN Validator
Validate Ethiopian Revenue and Customs Authority (ERCA) TIN format
Finland VAT Number Validator
Validate Finnish arvonlisaveronumero (FI prefix + 8-digit Y-tunnus)
Finland Y-tunnus Validator
Validate Finnish business ID (Y-tunnus) with modulus check
France Postal Code Validator
Validate a French 5-digit code postal and map it to its département
France SIREN Validator
Validate a 9-digit French SIREN company number with the Luhn algorithm
France SIRET Validator
Validate a 14-digit French SIRET establishment code with the Luhn algorithm
France VAT Number Validator
Validate a French numéro de TVA: FR prefix, 2-digit key and SIREN
Germany PLZ Postal Code Validator
Validate German 5-digit Postleitzahlen and map them to a federal state
Germany VAT Number Validator
Validate a German USt-IdNr (DE + 9 digits) with the MOD-11,10 check
Ghana TIN Validator
Validate Ghanaian GRA Tax Identification Numbers (Ghana Card PIN format).
Greece AFM Tax Number Validator
Validate a Greek taxpayer number (ΑΦΜ) with the modulus-11 check
Greece VAT Number Validator
Validate a Greek EL VAT number (EL + 9-digit AFM)
BCP 47 Language Tag Lookup & Validator
Validate and look up BCP 47 language tags for the HTML lang attribute
Hungary TAJ Number Validator
Validate a Hungarian social security (TAJ) number with the weighted mod-10 check.
Hungary VAT Number Validator
Validate a Hungarian ÁFA / ANUM VAT number (HU + 8 digits).
India GSTIN Validator
Validate Indian GST Identification Numbers with check digit
India IFSC Code Validator
Validate Indian Financial System Codes (IFSC) for NEFT, RTGS and IMPS bank routing.
India Mobile Number Validator
Validate Indian 10-digit mobile numbers and detect the access provider
Indonesia NIK Validator
Validate the 16-digit Indonesian national ID (NIK) and decode its fields.
Ireland VAT Number Validator
Validate Irish VAT numbers in all four known formats with the mod-23 check letter.
Israel ID Number (ת.ז.) Validator
Validate a 9-digit Israeli identity number (Teudat Zehut) with the Luhn check digit.
Israel VAT Number Validator
Validate an Israeli VAT / company number (עוסק מורשה) with the official check-digit rule.
Italy Partita IVA Validator
Validate Italian VAT numbers with the official Luhn-variant check
Italy CAP Postal Code Validator
Validate Italian CAP codes and map them to a postal area
Japan Corporate Number Validator
Validate Japanese 13-digit corporate number (法人番号)
Japan My Number Validator
Validate Japanese individual number (My Number) check digit
Japan Phone Number Validator
Validate Japanese fixed-line, mobile (keitai) and IP phone numbers
Kenya KRA PIN Validator
Validate a Kenya Revenue Authority PIN — letter, 9 digits, letter format.
Keyboard Shortcut Conflict Checker (WCAG 2.5.4)
List your app's keyboard shortcuts and flag conflicts with AT and browser defaults
Landmark Region Completeness Checker
Paste HTML and verify your page has the required ARIA landmark regions
Markdown Accessibility Checker
Paste Markdown and flag empty alt text, skipped headings, and bare URLs
Mexico Phone Number Validator
Validate Mexican 10-digit numbers: 2 or 3-digit LADA plus local
Mexico Postal Code Validator
Validate Mexican 5-digit códigos postales by state prefix
Mexico RFC Validator
Validate Mexican RFC for individuals and companies
Netherlands KvK Number Validator
Validate Dutch Chamber of Commerce numbers with the 11-proef
Netherlands Postal Code Validator
Validate a Dutch postcode in the 4-digit + 2-letter NNNN AA format.
Netherlands VAT Number Validator
Validate a Dutch BTW-nummer: NL + 9 digits + B + 2-digit suffix.
Nigeria TIN Validator
Validate Nigerian Tax Identification Numbers (FIRS/JTB format).
Norway MVA (VAT) Number Validator
Validate Norwegian momsregistreringsnummer (9-digit org number + MVA)
Norway Organisasjonsnummer Validator
Validate Norwegian 9-digit company numbers with weighted modulus-11
Norway Postnummer Validator
Validate a Norwegian 4-digit postnummer and map it to its region
Open Graph Tag Privacy Auditor
Paste HTML head tags and flag OG or Twitter card data that may over-expose content
OWASP Top 10 Self-Audit Checklist
Walk through all 10 OWASP 2021 categories with per-item pass and fail tracking
Pakistan NTN Validator
Validate Pakistani National Tax Numbers issued by FBR — format and check digit
Password Manager Readiness Checker
Paste a login form and check if it is correctly structured for password manager autofill.
Password Policy Compliance Tester
Define a password policy and test candidate passwords against every rule
Peru RUC Validator
Validate a Peruvian tax registration code (RUC) with the SUNAT mod-11 check digit.
Philippines SSS Number Validator
Validate Philippine Social Security System numbers (format + Luhn check)
Poland NIP Validator
Validate a Polish tax identification number (NIP) with the weighted mod-11 check digit.
Poland Postal Code Validator
Validate a Polish NN-NNN kod pocztowy and map it to a voivodeship
Poland REGON Validator
Validate a Polish statistical business number (REGON, 9 or 14 digits).
Portugal IBAN Validator
Validate a Portuguese IBAN (PT50 + 21 chars) with MOD-97
robots.txt Privacy Auditor
Paste a robots.txt and check AI crawler rules and accidental path exposure
Romania CIF/CUI Validator
Validate Romanian company tax codes (CIF/CUI) with the official ANAF check digit.
Russia Postal Code Validator
Validate a Russian 6-digit индекс and map it to a federal subject
Russia SNILS Validator
Validate an 11-digit Russian pension insurance number (СНИЛС) with its checksum.
Saudi National ID Validator
Validate Saudi national identity numbers with the Luhn check digit
Saudi Arabia VAT Number Validator
Validate Saudi ZATCA VAT registration numbers (15 digits)
Screen Reader Announcement Simulator
Paste HTML and preview what JAWS or NVDA would announce per element
Session Timeout UX & Security Calculator
Calculate the optimal session timeout for a given risk level and user context.
Singapore NRIC/FIN Validator
Validate Singapore NRIC (S/T) and FIN (F/G/M) with the official weighted check
Singapore UEN Validator
Validate Singapore Unique Entity Numbers (Business, Company and Others).
Sitemap Privacy Auditor
Paste a sitemap.xml and flag URLs that expose user IDs, tokens, or internal paths
Slovakia Rodné číslo Validator
Validate a Slovak national ID (rodné číslo) — shared rules with the Czech birth number.
South Africa ID Number Validator
Validate a South African 13-digit ID number with the Luhn check digit.
South Africa VAT Number Validator
Validate a South African VAT vendor number — 10 digits starting with 4 plus Luhn.
South Korea Business Registration Number Validator
Validate Korean 10-digit business registration numbers (BRN)
Spain NIF/NIE Validator
Validate a Spanish NIF or NIE with the official modulo-23 letter table
Spain VAT Number Validator
Validate Spanish IVA numbers (ESX format) in full
Sri Lanka NIC Validator
Validate Sri Lankan old 9-char and new 12-digit NIC formats
Subdomain Naming Security Checker
Paste a list of your subdomains and flag ones that hint at sensitive internal services.
Sweden Organisationsnummer Validator
Validate a Swedish company registration number with the Luhn check.
Sweden Postnummer Validator
Validate Swedish 5-digit postal codes and map them to regions
Sweden VAT Number Validator
Validate a Swedish momsregistreringsnummer (SE + 12 digits).
Switzerland PLZ Validator
Validate a Swiss 4-digit Postleitzahl and map it to its canton zone
Switzerland UID Validator
Validate Swiss company identification number (UID / CHE)
Text Spacing Override Tester (WCAG 1.4.12)
Preview copy with WCAG 1.4.12 maximum text-spacing overrides applied
Thailand National ID Validator
Validate a Thai 13-digit national ID with the official mod-11 check digit.
Thailand Tax ID Validator
Validate Thai Revenue Department taxpayer IDs (13-digit check digit)
Turkey T.C. Kimlik No Validator
Validate an 11-digit Turkish national identity number (TCKN) with the official two-check-digit rule.
Turkey Vergi Kimlik No Validator
Validate a 10-digit Turkish taxpayer number (VKN) with the official check-digit algorithm.
UAE Tax Registration Number Validator
Validate UAE Federal Tax Authority TRN numbers (15 digits)
UK National Insurance Number Validator
Validate UK NINO format including the official reserved-prefix rules.
UK Sort Code Validator
Validate UK bank sort codes and identify the issuing bank.
UK UTR (Tax Reference) Validator
Validate UK Unique Taxpayer Reference numbers with the HMRC check digit.
Ukraine IPN (РНОКПП) Validator
Validate a 10-digit Ukrainian individual tax number (РНОКПП / ІПН) with its check digit.
US EIN Validator
Validate US Employer Identification Numbers by IRS prefix rules.
US ITIN Validator
Validate IRS Individual Taxpayer Identification Numbers.
US ABA Routing Number Validator
Validate US bank routing numbers with the ABA checksum
US Social Security Number Validator
Validate US SSN format and detect known-invalid patterns.
vCard Validator
Check VCF files for RFC 6350 compliance and highlight missing fields
Vietnam Citizen ID (CCCD) Validator
Validate Vietnamese 12-digit Citizen Identification Card numbers
Vietnam MST (Tax Code) Validator
Validate Vietnamese tax codes for enterprises and branches
Modal Dialog ARIA Pattern Checker
Paste a modal dialog HTML snippet and verify the required ARIA attributes
WCAG 2.2 New Criteria Checker
Paste HTML and check for the 6 new success criteria added in WCAG 2.2
WCAG Mobile Accessibility Checklist
Step through 40 mobile-specific WCAG and MWBP checks with pass/fail tracking.
HTML Parsing & ID Uniqueness Checker (WCAG 4.1.1)
Paste HTML and find duplicate IDs and nesting problems that break ARIA references
WCAG 2.1 Success Criteria Search
Search WCAG 2.1 A and AA success criteria by keyword or number
Frequently asked questions
Do these validators send my data anywhere?
No. Every validator runs entirely in your browser using the official format and check-digit rules. Nothing you enter is uploaded, stored or logged — safe for tax, bank and ID numbers.
What does 'valid' actually mean here?
It means the value passes the structural and check-digit rules for its type (length, prefix, checksum). It confirms the format is correct — not that the number is registered to a real, active entity.
Which countries and formats are covered?
VAT/GST numbers, IBANs and national IDs for many countries, plus VIN, postal/phone formats, accessibility (WCAG) and common data formats — each as its own dedicated checker.
Are they free?
Yes, completely free with no account, supported by unobtrusive ads.