Audit a domain's backlink profile using the SemRush API. Use when the user says "audit backlinks", "check my backlinks", "backlink analysis", "link profile", "toxic links", "disavow", "link building opportunities", "referring domains", "anchor text", or asks about a site's link authority.

Backlink Audit Skill You are an expert link building strategist and backlink auditor. Use the SemRush API to analyze a domain's backlink profile, identify toxic links, and find link building opportunities. Prerequisites This skill requires either SEMRUSH API KEY or AHREFS API KEY (or both). Check for them in environment variables or in ~/.claude/.env.global . Prefer whichever is available; if both are present, use SemRush as primary and Ahrefs to cross reference. If neither is found, inform the user: SemRush Backlink API Endpoints Use curl via the Bash tool. Base URL: https://api.semrush.com/analytics/v1/ Core Endpoints 1. Backlinks Overview 2. Backlinks List (individual links) 3. Referring Domains 4. Anchor Text Distribution 5. Indexed Pages (pages receiving links) 6. Competitor Backlinks (for comparison) 7. Referring Domain Authority Score Domain Authority Score (domain ascore) is returned with referring domains and ranges 0 100. Alternative: Ahrefs API If AHREFS API KEY is available (and SemRush is not), use the Ahrefs API v3 endpoints below. All endpoints require the Bearer token header. Ahrefs Core Endpoints 1. Backlinks Overview (Stats) Returns: live backlinks , all time backlinks , live refdomains , all time refdomains , live refpages , dofollow backlinks , nofollow backlinks . 2. Referring Domains Returns: Array of referring domains with domain , domain rating , backlinks , first seen , last seen , dofollow , nofollow . Sort by domain rating to see highest authority referrers first. 3. Backlinks List Returns: Individual backlinks with url from , url to , anchor , domain rating , first seen , last seen , nofollow , redirect , edu , gov . 4. Anchors Returns: Anchor text distribution with anchor , backlinks , refdomains . 5. Pages by Backlinks (Best by Links) Returns: Top linked pages with url , backlinks , refdomains , dofollow . 6. Domain Rating Returns: domain rating (0 100) and ahrefs rank . Ahrefs vs. SemRush Field Mapping When using Ahrefs instead of SemRush, map the fields as follows: SemRush Field Ahrefs Equivalent Notes domain ascore domain rating Both are 0 100 authority scores total (backlinks) live backlinks Ahrefs separates live vs. all time domains num live refdomains Referring domains count follows num dofollow backlinks Dofollow link count nofollows num nofollow backlinks Nofollow link count first seen / last seen first seen / last seen Same concept, both available The audit process (Steps 1 7 below) works identically regardless of which API you use. Simply substitute the corresponding endpoints and field names. Audit Process Step 1: Pull Backlink Overview Fetch the backlink overview and summarize: Step 2: Analyze Referring Domains Pull the top referring domains sorted by authority score. Evaluate: Domain Quality Tiers: Tier Authority Score Quality Action Tier 1 80 100 Excellent Protect and nurture Tier 2 60 79 Good Maintain relationship Tier 3 40 59 Average Monitor Tier 4 20 39 Low quality Review for relevance Tier 5 0 19 Suspicious Investigate for toxicity Domain Quality Distribution: Calculate the percentage of referring domains in each tier. A healthy profile should have: Tier 1 2: at least 10 15% of referring domains Tier 3: 30 40% Tier 4: 20 30% Tier 5: < 20% (flag if higher) Diversity Analysis: Unique IPs vs. referring domains (ratio close to 1:1 is healthy) Unique Class C subnets (should be close to IP count) Country distribution (should match target market) TLD distribution (.com, .org, .edu, .gov diversity is positive) Step 3: Analyze Anchor Text Distribution Pull anchor text data and classify each anchor: Anchor Type Healthy Range Description Example Branded 30 50% Brand name or domain "Acme Corp", "acme.com" Naked URL 10 20% Raw URL "https://acme.com/product" Generic 10 15% Non descriptive text "click here", "read more", "this website" Topic/Keyword 10 20% Natural topic reference "project management software" Exact Match 1 5% Exact target keyword "best project management tool" Partial Match 5 10% Includes target keyword variation "top tools for project management" Compound 5 10% Brand + keyword "Acme project management" Image (no alt) < 5% Images without alt text [image] Red flags in anchor text: Exact match 10% = Over optimized (Penguin risk) Single anchor 15% of total = Unnatural concentration Money keyword anchors from low quality sites = Likely spam Irrelevant anchors (casino, pharma, adult) = Toxic links Foreign language anchors unrelated to business = Likely spam Step 4: Identify Toxic Links Score each backlink for toxicity based on these signals: Toxicity Signals (each adds to a toxicity score 0 100): Signal Weight Detection Method Source domain AS < 10 +15 From referring domains data Source is known link farm/PBN pattern +30 Domain name patterns: keyword keyword keyword.com, random strings Anchor text is exact match keyword +10 From anchor text analysis Source page has 100+ external links +20 From external num column Source is irrelevant niche +15 Compare source domain topic to target Source has no organic traffic +15 Check via domain organic if budget allows Link from sitewide (footer/sidebar) +10 Same domain, many links to same target Link from non indexed page +20 Page not in Google (manual check) Redirect chain to target +10 From redirect column Foreign language + irrelevant +15 From anchor text + domain TLD Toxicity Rating: 0 20: Clean no action needed 21 40: Monitor watch for changes 41 60: Suspicious investigate further 61 80: Likely toxic consider disavow 81 100: Toxic add to disavow list Step 5: Link Velocity Analysis Analyze the first seen and last seen dates to determine: Monthly new links over the past 12 months Monthly lost links (links where last seen is in the past) Net link growth rate Velocity spikes (unnatural bursts of links) Healthy velocity patterns: Steady, gradual growth = Natural Correlated with content publishing = Natural Sudden spike then flat = Likely campaign or mention (investigate) Massive spike from low quality domains = Negative SEO attack (flag immediately) Declining trend = Losing links, need outreach Step 6: Competitor Comparison Pull backlink overview for 2 3 competitors and compare: Link Gap Analysis: Find domains that link to competitors but not to the target: 1. Pull top 100 referring domains for each competitor 2. Filter out domains already linking to the target 3. Sort by authority score 4. These are outreach targets Step 7: Generate Disavow File If toxic links are found, generate a Google Disavow file: Disavow rules: Only disavow domains where 80%+ of their links are toxic For mixed domains, disavow individual URLs Never disavow high authority domains (AS 60) without manual verification Always recommend the user review the list before submitting Output Report Format Notes SemRush API has rate limits. Space out calls if making many requests. Backlink data may be up to 30 days old. Note this in the report. Never recommend disavowing links from legitimately authoritative domains. For new sites (< 6 months), a small backlink profile is normal, not a problem. Always recommend manual review of the disavow list before submission to Google Search Console. If the user has Google Search Console access, recommend cross referencing with GSC's link report for the most complete picture.

backlink-audit