How do I check if a site is accessible to users and indexing robots?

Availability is the precondition for everything else. Yandex makes the consequence explicit: if the robot cannot reach the site because of a server error, the site may disappear from search results entirely — and for the same reason, visitors cannot reach it either.

The three checks

• Site diagnostics (Website optimisation → Site diagnostics), with a summary widget on the dashboard. This is where availability problems are reported first.
• Security and violations. Yandex connects security to availability directly: infected sites are typically blocked by antivirus software in the browser, and hosting providers often disable infected sites, making them unreachable for visitors and robots alike. A malware incident is an availability incident.
• Page check (Tools → Check page), which is the most informative of the three because it shows three different things at once.

What page check actually gives you

• A screenshot of the page as rendered on mobile and desktop, in the audit results tab.
• The text available to the indexing bot, under “page version in the database → page content”. This is the definitive answer to “can the robot read this page”.
• The response code, under technical information.

Yandex states the rule plainly: 200 OK means the page is accessible to bots and visitors; any other code means it is accessible to neither and cannot appear in search results.

How to use this

When a page is missing from search, check availability before anything else, and check it as the robot rather than in a browser. The screenshot and the stored page content together answer the two questions that matter — what it looks like, and what of it the engine can actually read — and the gap between them is where most surprises live.