The Web Design Group

Validator Differences

The WDG HTML Validator is similar in many ways to the W3C HTML Validation Service and the (now unavailable) WebTechs Validation Service. The WDG HTML Validator does not use any source code from the other validators, but all three validators use James Clark's nsgmls internally. While the three validators use different versions of nsgmls, the errors from all three should be the same in most cases. However, some differences may arise:

The three validators all differ significantly from other checking tools such as Weblint and CSE 3310 HTML Validator. (Despite its name, the latter is not a true "validator.") The three online validators check documents against a document type definition--a published, machine-readable document that facilitates an objective check of syntax against HTML standards. On the other hand, lints are subjective; they provide a more cursory syntax check while adding stylistic checks, such as warning about poorly supported features. Lints are useful tools, but they are not substitutes for HTML validation.