Formats & configs
Validate JSON, YAML, XML, and CSV locally so payloads and configs are clean and private.
Fast, private, free
Validate sensitive data without uploading a thing.
Every validator runs in your browser, so nothing leaves your device. Check JSON, passwords, cards, links, and metadata with clear rules, examples, and FAQs that show what is being checked and why.
- ✔ Data never stored or sent
- ✔ No accounts or downloads
- ✔ New validators added weekly
What can you check?
Sanity-check JSON or YAML before committing changes.
Score password strength locally, and keep secrets off the network.
Validate URLs, meta lengths, and titles before you publish.
Run Luhn checks on cards or IDs without exposing numbers.
Used by developers, security engineers, and content teams worldwide.
Security & data sanity
Score passwords, run Luhn checks, and verify IDs without sending secrets or PII to any server.
Web & content checks
Inspect URLs, meta lengths, and word counts before publishing or sending to clients, with no screenshots or uploads required.
Browse by topic
Pick a validator category
Formats, security, developer utilities, text, data, web, and metadata. Each category links to validators teams use to catch issues before release.
Format Validators•25+ tools
Debug failing deploys
Validate JSON, YAML, XML, CSV, and HTML with instant syntax checks and prettified output for quick fixes.
Example validators
Developer Validators•30+ tools
Test a regex before merging
Everyday developer helpers like regex tests, UUID checks, and IP/port validation for quick sanity checks.
Security Validators•20+ tools
Raise password quality
Password strength, entropy, and token format checks that never leave your browser.
Example validators
- Password Strength Checker
- Password Entropy Calculator
- Hash Generator (MD5 / SHA1 / SHA256)
- Credit Card Validator
- SSH Public Key Validator
- PGP Public Key Validator
- PEM Certificate Validator
- X.509 Certificate Inspector
- Certificate Expiry Validator
- API Key & Token Validator
- bcrypt Hash Validator
- HMAC Generator & Validator
- IMEI Validator
- Postal/ZIP Code Validator
- SSN Format Validator
- ICCID (SIM) Validator
- Country Code Validator
- Currency Code Validator
- Language Code Validator
- JWT Signature Validator (HS256)
- Meta Robots / X-Robots-Tag SEO Validator
- Timestamp Validator
- Timezone Validator
Text Validators•20+ tools
Hit content targets
Counters and readability tools for writers, marketers, and support teams.
Example validators
Data Validators•20+ tools
Validate customer input early
Validate IBANs, credit cards, ISBNs, VINs, and barcodes with checksum and pattern checks.
Web Validators•15+ tools
Publish with confidence
URL, sitemap, robots, and metadata checks for marketers and SEO teams.
Example validators
- URL Validator & HTTP Link Parser
- Sitemap XML Validator
- Open Graph & Twitter Card SEO Validator
- SPF Record Validator
- CSP SEO Validator & Content Security Policy Hardening Checker
- HTTP Compression Validator
- Security Headers SEO Validator & Public Site Hardening Checker
- CORS SEO Validator — API Origin Trust Checker
- Viewport Meta SEO Validator
- MX Record Validator
- Set-Cookie Header Validator
- URL List Validator
- Image Alt Text Validator
- Form Accessibility Validator
- ARIA Label Validator
- HTML Meta SEO Validator
- JSON-LD SEO Validator & Rich Result Schema Checker
- Meta Robots / X-Robots-Tag SEO Validator
- AMP Essentials Validator
- UTM Parameter Validator
- Referrer-Policy Validator
Metadata Validators•10+ tools
Prep assets for handoff
Image, audio, and file metadata checks to confirm dimensions, bitrate, or EXIF details without uploading to a server.
Example validators
- Image Dimension Validator
- Aspect Ratio Checker
- Audio Bitrate Validator
Launching soon, see wave schedule
Start here
High-demand validators
These are the core browser-local tools people come back for: web metadata checks, JSON and Markdown checks, ports, VINs, and IMEIs. They are linked directly from the homepage so crawlers and users can reach the most useful validators in one step.
web
Web App Manifest SEO Validator & PWA Install QA
Validate manifest.json locally for PWA installability, mobile install metadata, app names, start_url, display mode, theme colors, and icon entries before launch.
Open validator →format
Plist Validator
Validate Apple plist files (XML or binary/base64) locally with clear errors.
Open validator →web
JSON-LD SEO Validator & Rich Result Schema Checker
Validate rendered JSON-LD structured data for schema.org syntax, rich-result readiness, visible-content alignment, and crawlable schema blocks before publishing.
Open validator →data
IMEI Validator
Validate IMEI numbers with Luhn checksum client-side.
Open validator →data
VIN Validator
Validate Vehicle Identification Numbers (VIN) with checksum and metadata hints.
Open validator →developer
Port Validator
Check port numbers for valid ranges before using them in configs.
Open validator →format
Markdown Validator
Lint Markdown locally with remark-lint, surface rule IDs/line numbers, and keep content private.
Open validator →format
HTML Validator (light)
Check HTML structure with HTMLHint rules—mismatched tags, casing, and basic issues—all client-side.
Open validator →format
JSON Validator & Syntax Checker
Check JSON syntax, catch trailing commas and quote errors, and keep every payload local to your browser.
Open validator →Featured picks
Most-requested validators this week
Start with these popular tools, or open a category hub to browse every validator we’ve launched.
format
JSON Validator & Syntax Checker
Check JSON syntax, catch trailing commas and quote errors, and keep every payload local to your browser.
Open validator →web
Sitemap XML Validator
Validate sitemap.xml launch and indexation signals locally: urlset/index roots, absolute loc URLs, lastmod hygiene, and crawler discovery readiness.
Open validator →web
robots.txt Crawl Control Validator
Validate robots.txt crawl control rules, sitemap hints, and staging-to-production indexing directives locally before launch.
Open validator →web
Open Graph & Twitter Card SEO Validator
Validate rendered Open Graph and Twitter/X card tags for search-result snippets, social previews, share-card images, absolute URLs, and launch QA before publishing.
Open validator →Recently added
Hot off the roadmap
We publish new validators every wave. Here are the latest across formats, security, and web.
Why people bookmark us
Validation that protects privacy and saves time.
Private by design
Runs fully in the browser with no storage or logging, so payloads, tokens, and drafts stay local.
Transparent rules
Every tool shows the rules, examples, FAQs, and disclaimers so you know how results are made.
Always current
New validators ship every wave. Request one from the contact page and we’ll prioritize it.