Quick answer

Review the WCAG Contrast Checker & Calculator validation contract, malformed-input categories, semantic checks, error-recovery steps, and destination-system verification requirements.

Scope: This reference separates syntax checks, structural checks, semantic checks, and destination-system validation for WCAG Contrast Checker & Calculator. A successful result confirms only the checks documented by the tool.

Input contract

WCAG Contrast Checker & Calculator helps you validate WCAG color contrast against its documented syntax, structure, required fields, and common edge cases, with precise issues instead of a generic pass/fail directly in the browser where supported. Start with the built-in example, test valid and malformed input, review every warning, and verify the final result in the system that will consume it.

Supported formats: Unicode text, locale data, HEX colors

Validation layers

  • Syntax: characters, delimiters, quoting, encoding, and parseability.
  • Structure: required fields, value types, nesting, ordering rules, and cross-field consistency.
  • Semantics: identifiers, units, references, dates, ranges, permissions, or version-specific meaning.
  • Destination checks: the native parser, compiler, runtime, provider, browser, database, schema, or policy that ultimately consumes the result.

Malformed-input categories

  • Empty input, whitespace-only input, truncated content, or a missing required field.
  • Invalid Unicode, mixed encodings, invisible characters, unexpected line endings, or malformed escape sequences.
  • Duplicate keys or records, unsupported versions, out-of-range values, excessive nesting, or oversized files.
  • Correct syntax with incorrect business meaning, permissions, authentication, trust, units, references, or environment-specific values.

Expected error handling

  • Start with the first reported error; later messages can be side effects of the same malformed input.
  • Reduce the input to the smallest example that still reproduces the problem.
  • Check hidden whitespace, line endings, Unicode normalization, quoting, delimiters, and file encoding.
  • Reload the built-in example to confirm that the WCAG Contrast Checker & Calculator workspace itself is operating normally.
  • For large files, test a smaller sample and monitor browser memory before processing the complete document.

Release checklist

  • Confirm that the input format and character encoding match the tool description.
  • Use a known-good example and a deliberately invalid example before trusting the workflow.
  • Compare important identifiers, numeric values, ordering, and whitespace-sensitive fields before and after the operation.
  • Do not treat readable or well-formatted output as proof that it is semantically correct.
  • Run the result through the native validator, compiler, runtime, browser, or application that will consume it.

Limitations

WCAG Contrast Checker & Calculator operates within browser memory and the web-platform APIs available in the current browser. Very large, deeply nested, encrypted, proprietary, or malformed inputs can exceed those limits. The checks cover the documented deterministic rules; destination systems can enforce additional versions, extensions, schemas, or policies.

See the WCAG Contrast Checker & Calculator documentation for the current feature contract.

Next step: Open WCAG Contrast Checker & Calculator or read its complete documentation.