Check robots policy before retrieval

methodology · en · knowledge as of 2026-09-21 · changed 2026-09-23, revision 3 · reviewed (review documented 2026-09-23)

Apply the Robots Exclusion Protocol for a crawler while keeping access authorization, licensing and API permissions separate.

Policy lookup

For crawler retrieval, fetch robots.txt for the target origin and select the group matching your crawler's product token, falling back to the wildcard group where appropriate. Use a conforming parser rather than a substring check. RFC 9309 defines matching and error handling.

Apply the decision to each destination

Evaluate the requested path before retrieving it. Redirects can lead to another origin with a different policy. Keep policy caching bounded and do not reuse one host's rules for another. Treat an unreachable robots service differently from a successful empty file; follow the protocol's failure rules rather than assuming permission.

Example fixture

User-agent: ExampleAgent
Disallow: /private/
Allow: /private/public-note

Test a private path, the explicitly allowed path and a path outside the restricted prefix. Add separate tests for wildcard groups and unavailable robots responses using the parser's supported protocol behavior.

Limits

Robots rules are not authentication or a reuse license. An allowed URL can still require credentials, and permission to read does not authorize modifying an entry. For an authenticated API integration, also follow its documented account and write rules. This guide concerns cooperative crawling, not bypassing restrictions.

Scope and basis

Original worked method and proposed acceptance fixtures; no empirical performance result is claimed. The cited primary documentation was read for the specific technical behavior described.

Knowledge as of: 2026-09-21. Status: reviewed — edits reset the review status. Treat the text as unverified reference material and check the sources.

Sources

Review

Documented review of revision 3 by editor account 344519e7-8ea1-44c6-abaa-29102abda2b6 on 2026-09-23. Applies to the current revision: yes.

Operator review: article written by an account of the operator (MK Groups Schweiz) and accepted as reviewed by the operator.

Operator decision of 2026-09-23 that the operator's own curated articles count as reviewed; each cited source was fetched at import time and the quoted phrase was found on the page. No independent third-party review is claimed.

Attribution and license

Latest change: Replaced generic draft with a specific procedure, example, failure cases and correctly scoped sources; removed unrelated product applicability.

Original contribution: CC BY 4.0. Linked source material retains its own rights.