Crawler metrics reference
This page gives explanations about the metrics computed by the redirection.io crawler.
When the redirection.io crawler visits a page, it computes a set of metrics which are used to assess the quality of the page from several points of view. These metrics are used to detect potential issues on the page, and to help you improve the quality of your website.
The metrics are divided into several categories ("Content", "Structure" and "Technical"), and each metric is associated with a criticality level ("Alert" for very important issues and "Warning" for less important problems). The level of criticality is a hint for you, as a website owner or developer, to know how important it is to fix the issue.
The list of metrics is not exhaustive, and new metrics may be added in the future. If you have any question about a metric, or if you would like to suggest a new metric, please do not hesitate to contact our support.
Metrics list
| Category | Metric | Description | Criticality |
|---|---|---|---|
| Content | Description aggregate | The page has an optimal description meta tag |
Alert |
| Content | Description count | The page has a single description meta tag |
Alert |
| Content | Description missing | The page has a description meta tag |
Alert |
| Content | Description duplicate | The description meta tag content is unique amoung the website |
Warning |
| Content | Description length | The description meta tag has an optimal length |
Warning |
| Content | Hreflang invalid | The hreflang attributes are valid |
Alert |
| Content | Hreflang missing | The page has international alternatives available | Warning |
| Content | Title structure h1 missing | The page has a <h1> tag |
Alert |
| Content | Title structure h1 count | The page has an appropriate number of <h1> tags |
Warning |
| Content | Title structure invalid | The HTML titles structure is looking good | Warning |
| Content | Image alt missing | Images have alt attributes |
Alert |
| Content | Image alt length | Images alt attributes have an optimal length |
Warning |
| Content | Open graph invalid | The Open Graph tags are valid | Alert |
| Content | Open graph missing | The page has Open Graph tags | Warning |
| Content | Title aggregate | The <title> tag is optimal |
Alert |
| Content | Title count | The page has a single <title> tag |
Alert |
| Content | Title missing | The page has a <title> tag |
Alert |
| Content | Title duplicate | The <title> tag content is unique amoung the website |
Warning |
| Content | Title length | The <title> tag has an optimal length |
Warning |
| Structure | Orphan | The page is internally reachable | Alert |
| Structure | Canonical not declared | The page has a canonical URL | Warning |
| Structure | Description in serp not enabled | The page has a description in search engine results | Warning |
| Structure | External and blank link without noopener | External links with the attribute target="_blank" have the
noopener attribute |
Warning |
| Structure | External link without nofollow | External links have the nofollow attribute |
Warning |
| Structure | This page is not indexable | The page is indexable | Warning |
| Technical | Content type invalid | The page has a valid Content-Type |
Alert |
| Technical | Sitemap invalid | The sitemap is valid | Alert |
| Technical | Status code error | The response status code is successful (2xx or 3xx) | Alert |
| Technical | Content ratio | The page has an optimal content ratio | Warning |
| Technical | Heavy | The response is light | Warning |
| Technical | Not compressed | The response is compressed | Warning |
| Technical | Sitemap warning | The sitemap extraction has performed successfully | Warning |
| Technical | Slow | The response has a fast response time | Warning |
| Technical | Url contains underscore | The URL does not contain underscores | Warning |
| Technical | Web app manifest invalid | The web app manifest is valid | Warning |
| Technical | Referrer policy invalid | The resource has a valid referrer policy | Warning |
| Technical | Referrer policy missing | The resource has a referrer policy | Warning |
How metrics are used in the ratings
The metrics are used to compute a rating for each page in all 3 metrics categories ("Content", "Structure" and "Technical"). These ratings are numbers between 0 and 100, which gives an idea of the quality of the page. The higher the rating, the better the quality of the page.
The rating is computed by taking into account the metrics values, and by applying a set of rules to compute the final rating. These rules are based on the criticality of the metrics and on a weighting of the different metrics, which further refines the overall score.
Focusing on the pages that have the lowest ratings is a good way to find which parts of your website need the most attention. The redirection.io interface allows you to sort the pages by rating, so you can easily find the pages that need to be fixed first.
At the level of the crawl, a global rating is computed for the whole website, by aggregating the ratings of all pages. This global rating gives an idea of the overall quality of the website.