Audit Standard / 2026.4

Rule explorer: Audit Standard 2026.4

Every check that defines technical readiness in MaxiMarket Audit Standard 2026.4, exactly as the audit applies it. Open a rule to see what it checks, why it matters, how to fix it, where its authority comes from and how much it counts.

Guides by topic: technical SEO audit rules, AI readiness, structured data and ecommerce product data.

Version: 2026.4
Status: Current
Published: 2026-10-01
Rules: 94
Scored: 74
Observations: 34

Authority levels

Official search-engine requirement: A search engine documents it as required for a specific outcome, such as Google eligibility.; Strongest external authority
Open standard / Schema.org: Defined by an open standard or vocabulary: HTML, WCAG, IETF RFCs, Schema.org, Sitemaps, Open Graph.
Official platform recommendation: Recommended in official platform documentation, such as Google Search Central or an AI platform.
Accepted best practice: Widely accepted practice with a cited source, but no official requirement.
MaxiMarket recommendation: MaxiMarket’s own advice. Never presented as a search engine or platform requirement.; MaxiMarket methodology

Filter

Showing 14 rules and 0 observations.

Rules

Rules pass or fail. A failed rule becomes a finding in your report; scored rules also count toward the Technical Score.

Document metadata

SEO-CHARSET-001Open standard / Schema.org · RequiredCharacter encoding is declared once, as UTF-8DocumentWarning when failedWeight 2Technical SearchAI DiscoveryMachine Readability

What this checks: The meta charset elements: how many there are and their value.
Why it matters: HTML allows at most one meta charset element and only the value utf-8; a wrong or conflicting declaration can garble text for every consumer.
How to fix: Keep a single <meta charset="utf-8"> and serve the document as UTF-8.

Expected: At most one meta charset, with the value utf-8.
Applies to: Pages with at least one meta charset element.
Authority: Open standard / Schema.org · RequiredHTML Standard, for pages that declare meta charset.
Technical Score: Weight 2 of 3A wrong or conflicting encoding declaration can garble the text for every consumer.
How MaxiMarket detects it: Reports when there is more than one meta element with a charset attribute, or its value is not utf-8 (ASCII case-insensitive, surrounding whitespace ignored). Pages without meta charset are not applicable.
Sources: HTML Standard: character encoding declaration — WHATWG, verified 2026-09-26

SEO-LANGUAGE-001Open standard / Schema.org · RequiredPage language is declaredDocumentWarning when failedWeight 2Technical SearchAI DiscoveryMachine Readability

What this checks: Whether the root html element has a non-empty lang attribute.
Why it matters: WCAG requires the default human language of a page to be programmatically determinable, and the HTML Standard encourages a lang attribute on the root element for speech synthesis and translation tools.
How to fix: Add a lang attribute with the page language to the <html> element.

Expected: The root <html> element declares the page language, such as lang="en".
Applies to: Every retrieved page.
Authority: Open standard / Schema.org · RequiredRequired for WCAG 2.2 Level A conformance (Success Criterion 3.1.1); the HTML Standard encourages the lang attribute.
Technical Score: Weight 2 of 3A WCAG Level A requirement for every page.
How MaxiMarket detects it: Reports when the first html element has no lang attribute or an empty one. The language value is not validated.
Sources: WCAG 2.2 Understanding SC 3.1.1 Language of Page — W3C, verified 2026-09-26

HTML Standard: the html element — WHATWG, verified 2026-09-26

SEO-LANGUAGE-002Open standard / Schema.org · RequiredPage language is a well-formed BCP 47 tagDocumentWarning when failedWeight 1AI DiscoveryMachine Readability

What this checks: Whether the html lang value conforms to the BCP 47 (RFC 5646) language tag syntax.
Why it matters: HTML requires the lang value to be a valid BCP 47 language tag; a malformed tag cannot identify the language for assistive technology or language processing.
How to fix: Use a BCP 47 language tag, such as en, en-GB or zh-Hant.

Expected: The lang value is a valid BCP 47 language tag, such as en or de-CH.
Applies to: Pages whose html element has a non-empty lang attribute.
Authority: Open standard / Schema.org · RequiredRequired by the HTML Standard for the lang attribute.
Technical Score: Weight 1 of 3A malformed lang value is declared but unusable; it only applies when lang is present.
How MaxiMarket detects it: Reports when a non-empty lang value is not well-formed under the RFC 5646 ABNF (language, script, region, variant, extension and private-use subtags, private-use tags and the listed grandfathered tags), case-insensitively. Subtags are not checked against the IANA registry, so a well-formed but unregistered tag passes.
Sources: HTML Standard: the lang and xml:lang attributes — WHATWG, verified 2026-09-26

RFC 5646 (BCP 47): Tags for Identifying Languages — IETF, verified 2026-09-26

Canonicalization

SEO-CANONICAL-002Open standard / Schema.org · RequiredOnly one canonical is declaredDocumentWarning when failedWeight 2Technical SearchAI Discovery

What this checks: The number of rel=canonical link elements, and of canonical entries in HTTP Link headers.
Why it matters: RFC 6596 asks for a single canonical; when several are declared, Google may ignore them.
How to fix: Keep a single rel=canonical link element (and at most one canonical Link header).

Expected: At most one canonical per method.
Applies to: Pages that declare at least one canonical, in a link element or an HTTP Link header.
Authority: Open standard / Schema.org · RequiredRFC 6596 and Google canonicalization guidance.
Technical Score: Weight 2 of 3Several canonical declarations may make search engines ignore all of them.
How MaxiMarket detects it: Reports when the HTML contains more than one link element whose rel includes canonical, or the HTTP Link headers contain more than one rel=canonical entry. Disagreement between the two methods is SEO-CANONICAL-008.
Sources: RFC 6596: The Canonical Link Relation — IETF, verified 2026-09-26

How to specify a canonical URL — Google Search Central, verified 2026-09-26

SEO-CANONICAL-006Open standard / Schema.org · RecommendedCanonical target is directly retrievableDocumentWarning when failedWeight 2Technical SearchAI Discovery

What this checks: The HTTP status of the canonical URL when it differs from the final URL.
Why it matters: RFC 6596 advises against canonical targets that redirect or return an error, and Google wants canonical URLs that are accessible and indexable.
How to fix: Point the canonical at the final, directly reachable URL of the preferred page.

Expected: HTTP 200 without a redirect.
Applies to: Pages whose declared canonical resolves to a different URL than the final URL.
Authority: Open standard / Schema.org · RecommendedRFC 6596 and Google canonicalization guidance.
Technical Score: Weight 2 of 3A canonical that redirects or errors points search engines at a URL they cannot use.
How MaxiMarket detects it: One bounded request to the canonical URL through the same destination checks as the audit (public HTTP(S) destinations only, no redirects followed, 5-second limit). Reports a redirect status or a 4xx. Server errors, throttling, timeouts and refused destinations are not evaluated.
Sources: RFC 6596: The Canonical Link Relation — IETF, verified 2026-09-26

How to specify a canonical URL — Google Search Central, verified 2026-09-26

SEO-CANONICAL-007Open standard / Schema.org · RecommendedCanonical target does not declare another canonicalDocumentWarning when failedWeight 1Technical SearchAI Discovery

What this checks: The canonical declared by the canonical target page.
Why it matters: RFC 6596 advises against chains of canonical designations; search engines may ignore a chained canonical.
How to fix: Point the canonical directly at the final preferred URL.

Expected: The target is its own canonical, or declares none.
Applies to: Pages whose canonical target was retrieved as HTML with HTTP 200.
Authority: Open standard / Schema.org · RecommendedRFC 6596 guidance.
Technical Score: Weight 1 of 3A chained canonical may be ignored, but the chain usually still reaches the preferred page.
How MaxiMarket detects it: Uses the same request as SEO-CANONICAL-006. When the target answers 200 with HTML (read up to 512 KiB), reports when its first canonical link element resolves to a URL other than the target itself.
Sources: RFC 6596: The Canonical Link Relation — IETF, verified 2026-09-26

Images and media

MEDIA-IMG-ALT-001Open standard / Schema.org · RequiredImages have text alternativesDocumentWarning when failedWeight 1Technical SearchAI DiscoveryMachine Readability

What this checks: img elements without an alt attribute.
Why it matters: WCAG 1.1.1 (Level A) requires a text alternative for non-text content, and Google calls alt text the most important image metadata.
How to fix: Add an alt attribute to every img: a description for meaningful images, alt="" for decorative ones.

Expected: Every img has an alt attribute (empty for decorative images).
Applies to: Pages with at least one img element.
Authority: Open standard / Schema.org · RequiredWCAG 2.2 Level A.
Technical Score: Weight 1 of 3A WCAG Level A requirement and Google image guidance. Lowered to 1 in 2026.3: the search effect depends on each image's role, and decorative images correctly use alt="".
How MaxiMarket detects it: Reports when an img element has no alt attribute and no other accessible name or hiding: aria-label, aria-labelledby, role="presentation" or role="none", and aria-hidden="true" are accepted. Alt text quality is not judged.
Sources: WCAG 2.2 Understanding SC 1.1.1 Non-text Content — W3C, verified 2026-09-26

Google image SEO best practices — Google Search Central, verified 2026-09-26

HTML Standard: requirements for providing text to act as an alternative for images — WHATWG, verified 2026-09-26

Sitemaps

INDEX-SITEMAP-002Open standard / Schema.org · RequiredSitemap is well-formedIndexingWarning when failedWeight 2Technical SearchAI Discovery

What this checks: Whether each retrieved sitemap is well-formed XML with a urlset or sitemapindex root.
Why it matters: The Sitemaps protocol defines a sitemap as XML beginning with urlset (or sitemapindex for index files); a malformed file cannot be processed as a sitemap.
How to fix: Regenerate the sitemap as well-formed UTF-8 XML following the Sitemaps protocol.

Expected: Each sitemap is a well-formed XML document whose root is urlset or sitemapindex.
Applies to: Origins where at least one sitemap was retrieved.
Authority: Open standard / Schema.org · RequiredRequired by the Sitemaps XML format.
Technical Score: Weight 2 of 3A malformed sitemap cannot be processed at all.
How MaxiMarket detects it: Reports when at least one retrieved sitemap is malformed, has another root element, or contains a DTD or entity declaration, which MaxiMarket rejects for safety. Gzip-compressed sitemaps are not supported and namespaces are not validated.
Sources: Sitemaps XML format — Sitemaps.org, verified 2026-09-26

INDEX-SITEMAP-007Open standard / Schema.org · RecommendedSitemap lastmod values are valid W3C DatetimeIndexingInfo when failedWeight 1Technical SearchAI Discovery

What this checks: The format of lastmod values in the inspected sitemaps.
Why it matters: The sitemap protocol requires W3C Datetime; Google uses lastmod only when it is consistently accurate, and a malformed value cannot be used.
How to fix: Write lastmod as YYYY-MM-DD or as a full timestamp with a time zone, such as 2026-09-26T08:00:00+00:00.

Expected: W3C Datetime: YYYY, YYYY-MM, YYYY-MM-DD, or a date with hh:mm[:ss[.s]] and a time zone.
Applies to: Retrieved, well-formed sitemaps with at least one lastmod value.
Authority: Open standard / Schema.org · RecommendedSitemaps XML protocol.
Technical Score: Weight 1 of 3Malformed lastmod values are ignored; the URLs are still listed.
How MaxiMarket detects it: Reports when a lastmod of an inspected url or sitemap entry does not match a W3C Datetime form or has an impossible date or time. Whether the dates are accurate is not verifiable and not checked.
Sources: Sitemaps XML format — Sitemaps.org, verified 2026-09-26

Build and submit a sitemap — Google Search Central, verified 2026-09-26

Structured data (general)

STRUCTURED-JSONLD-002Open standard / Schema.org · RequiredJSON-LD blocks parse as JSONStructured dataWarning when failedWeight 2Technical SearchAI DiscoveryMachine Readability

What this checks: Whether each inspected JSON-LD block parses as JSON.
Why it matters: JSON-LD is JSON; a block that cannot be parsed cannot be read as structured data by any consumer.
How to fix: Validate the JSON-LD block and fix syntax errors such as trailing commas, unescaped quotes or unclosed brackets.

Expected: Every JSON-LD block is valid JSON.
Applies to: Pages with at least one JSON-LD block.
Authority: Open standard / Schema.org · RequiredRequired by the JSON-LD 1.1 data format.
Technical Score: Weight 2 of 3An unparseable JSON-LD block loses all the data it contains.
How MaxiMarket detects it: Reports when at least one inspected JSON-LD block fails JSON parsing. Blocks skipped because of size or count limits are not counted as invalid.
Sources: JSON-LD 1.1 — W3C, verified 2026-09-26

Product and Offer data

STRUCTURED-OFFER-006Open standard / Schema.org · RecommendedOffer price is machine-readableOfferWarning when failedWeight 2Technical SearchAI DiscoveryCommerceMachine Readability

What this checks: The format of Offer price and priceSpecification.price values, and AggregateOffer lowPrice and highPrice.
Why it matters: Schema.org asks for "." as the decimal separator and for the currency in priceCurrency, not in the price.
How to fix: Write prices such as 1299.00, without currency symbols or thousands separators.

Expected: A number, or a string of digits with an optional "." decimal part.
Applies to: Pages with at least one inspected Offer or AggregateOffer price value linked from a fully inspected Product.
Authority: Open standard / Schema.org · RecommendedSchema.org Offer usage guidance.
Technical Score: Weight 2 of 3A price that is not machine-readable cannot be interpreted reliably.
How MaxiMarket detects it: Reports when an inspected price value (linked from a fully inspected Product) is neither a finite non-negative JSON number nor a string of digits with an optional "." and digits (surrounding whitespace ignored). Missing prices are STRUCTURED-OFFER-001 and -002.
Sources: Schema.org Offer — Schema.org, verified 2026-09-26

STRUCTURED-OFFER-008Open standard / Schema.org · RecommendedpriceValidUntil is not in the pastOfferWarning when failedWeight 1Technical SearchAI DiscoveryCommerceMachine Readability

What this checks: priceValidUntil of each inspected Offer against the audit time.
Why it matters: After priceValidUntil the price is by definition no longer available, so the offer information is stale.
How to fix: Update or remove priceValidUntil.

Expected: Absent, or not yet passed.
Applies to: Pages with at least one inspected Offer declaring priceValidUntil.
Authority: Open standard / Schema.org · RecommendedSchema.org Offer definition; Google merchant listing recommendation.
Technical Score: Weight 1 of 3An expired priceValidUntil makes offer data stale.
How MaxiMarket detects it: Reports when an ISO 8601 priceValidUntil has passed in every time zone at the audit time (a date is valid through its whole day). Unparseable values are not evaluated.
Sources: Schema.org Offer — Schema.org, verified 2026-09-26

Merchant listing structured data — Google Search Central, verified 2026-09-26