Castov vs ValidateHTML

A side-by-side comparison built from both listings. Blank cells mean the company has not given that detail; we never guess.

Castov compared with ValidateHTML
Detail	Castov	ValidateHTML
What it does	Fast, 100% client-side developer platform with zero-data logging	HTML validation API and free online validator for deployed pages
Stage	Not given	Not given
Founded	Not given	Not given
Based in	Not given	FR
Pricing model	Free	Freemium
Pricing	All tools are free with no usage limits. The site may show ads in the future to cover running costs.	Free: unlimited validators and checkers, no account required, free site scans. Solo: 49 EUR per month including full site reports and monitoring of 1 site. Agency: 149 EUR per month including monitoring of 10 sites. Automatic fixes: from 3 EUR for 10 pages, 1 free fix daily without account. Full sit
Key features	Multi-timezone support with IANA database and daylight saving time JSON to TypeScript conversion JWT decoder and inspection Cron expression parser and generator End-to-end encrypted environment variable vaults P2P multiplayer canvas with WebRTC and CRDT Steganography for hiding encrypted secrets in images Service Worker API mocker for frontend testing Encrypted URL shares with hash fragment storage	Accessibility (WCAG) validation with machine-detectable failures HTML specification compliance checking Meta tags and viewport validation Open Graph checker Page weight measurement and compression analysis Single API endpoint with configurable checks Single verdict field for build pipeline integration Automatic AI-powered HTML fixes Weekly site audits with change notifications GitHub Actions integration
What makes it different	Zero-data logging: no keystroke sent to external servers, all processing in browser memory 100% client-side operation works entirely offline Unified ecosystem across web, CLI, and AI agents via MCP Server Sub-millisecond performance with local execution Tool chaining and piping for seamless multi-stage workflows	One API call runs five checks on a single page fetch instead of five separate requests Single boolean verdict for build pipelines to act on without parsing prose False-positive filtering eliminates unreliable findings Quality score based on issue variety, not count, capping best-practice impact Free tools remain unlimited without account or daily limits
Free plan	Not given	Not given
Open source	Not given	Not given
Platforms	Not given	Not given
Public API	Not given	Not given
Community votes	0	0
DR (Domain Rating by Ahrefs)	1 +1 (up) since last check	9 no change since last check
Trust Flow (Majestic)	1	10
Citation Flow (Majestic)	19	32
Referring domains (Majestic)	7	124

5 details filled in for both companies.

More alternatives to Castov More alternatives to ValidateHTML