Domain Filtering and Pattern Ignoring Strategies
Not every link in documentation needs or should be checked against the live internet. Internal development references, private network addresses, staging environments, intentionally deprecated URLs, and placeholder examples are common in technical writing. Attempting to validate these produces noise, wastes time, and can trigger false alarms. Smart filtering lets maintainers focus validation effort only on public, production-relevant links.
The Markdown Link Checker supports multiple layers of filtering. At the broadest level, users can define domain allow-lists and block-lists. An allow-list restricts checks to only approved domains, useful for organizations that want to limit external validation to trusted CDNs and partners. A block-list excludes known problem domains, such as localhost, internal company intranets, or services that reliably return four hundred twenty-nine rate limit responses.
Regex-Based Pattern Matching
For more granular control, regular expression patterns can ignore entire classes of URLs. Common patterns include skipping anything starting with http://localhost, https://127.0.0.1, file://, or mailto:. Patterns can also match versioned API paths that are known to change frequently or intentionally broken example URLs included for illustrative purposes. These rules are applied during the parsing phase so ignored links never reach the network layer.
Contextual and Inline Ignores
Sometimes filtering needs to be more precise than domain-wide rules. The tool recognizes special comments embedded directly in Markdown that instruct it to skip the next link or block of links. For example, a comment above a deprecated reference can mark it as intentionally broken. Inline attributes or special syntax can also tag individual links as private or test-only. This contextual approach gives authors fine-grained control without polluting global configuration files.
Balancing Coverage and Noise
Good filtering reduces false positives while preserving high confidence in the remaining results. Over-filtering risks missing real issues, so the tool provides reporting on ignored links for review. Maintainers can periodically audit skipped references to ensure nothing important slips through. When combined with allow-lists for CI environments, this strategy keeps validation fast, relevant, and trustworthy.
Effective ignoring transforms link checking from a noisy chore into a focused maintenance task. Teams spend less time triaging irrelevant alerts and more time fixing actual problems that affect real users.
The final article in this series explains how relative paths and in-page anchors are resolved and verified locally without network requests.