/backlink-audit

name: backlink-audit
description: 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:

This skill requires a SemRush or Ahrefs API key. Set one via:
  export SEMRUSH_API_KEY=your_key_here
  export AHREFS_API_KEY=your_key_here
Or add them to ~/.claude/.env.global

SemRush Backlink API Endpoints

Use `curl` via the Bash tool. Base URL: `https://api.semrush.com/analytics/v1/`

Core Endpoints

**1. Backlinks Overview**

https://api.semrush.com/analytics/v1/?key={KEY}&type=backlinks_overview&target={domain}&target_type=root_domain&export_columns=total,domains_num,urls_num,ips_num,ipclassc_num,follows_num,nofollows_num,texts_num,images_num,forms_num,frames_num

**2. Backlinks List (individual links)**

https://api.semrush.com/analytics/v1/?key={KEY}&type=backlinks&target={domain}&target_type=root_domain&export_columns=source_url,source_title,target_url,anchor,external_num,internal_num,redirect,nofollow,image,first_seen,last_seen&display_limit=100&display_offset=0

**3. Referring Domains**

https://api.semrush.com/analytics/v1/?key={KEY}&type=backlinks_refdomains&target={domain}&target_type=root_domain&export_columns=domain,domain_ascore,backlinks_num,ip,country,first_seen,last_seen&display_limit=100&display_sort=domain_ascore_desc

**4. Anchor Text Distribution**

https://api.semrush.com/analytics/v1/?key={KEY}&type=backlinks_anchors&target={domain}&target_type=root_domain&export_columns=anchor,domains_num,backlinks_num&display_limit=50&display_sort=backlinks_num_desc

**5. Indexed Pages (pages receiving links)**

https://api.semrush.com/analytics/v1/?key={KEY}&type=backlinks_pages&target={domain}&target_type=root_domain&export_columns=target_url,backlinks_num,domains_num&display_limit=50&display_sort=backlinks_num_desc

**6. Competitor Backlinks (for comparison)**

# Reuse endpoints above with competitor domain as target

**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)**

# Ahrefs backlinks overview
curl -s "https://api.ahrefs.com/v3/site-explorer/backlinks-stats?target={domain}&output=json" \
  -H "Authorization: Bearer ${AHREFS_API_KEY}"

Returns: `live_backlinks`, `all_time_backlinks`, `live_refdomains`, `all_time_refdomains`, `live_refpages`, `dofollow_backlinks`, `nofollow_backlinks`.

**2. Referring Domains**

# Ahrefs referring domains
curl -s "https://api.ahrefs.com/v3/site-explorer/refdomains?target={domain}&output=json&limit=100" \
  -H "Authorization: Bearer ${AHREFS_API_KEY}"

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**

curl -s "https://api.ahrefs.com/v3/site-explorer/backlinks?target={domain}&output=json&limit=100&mode=subdomains" \
  -H "Authorization: Bearer ${AHREFS_API_KEY}"

Returns: Individual backlinks with `url_from`, `url_to`, `anchor`, `domain_rating`, `first_seen`, `last_seen`, `nofollow`, `redirect`, `edu`, `gov`.

**4. Anchors**

curl -s "https://api.ahrefs.com/v3/site-explorer/anchors?target={domain}&output=json&limit=50&mode=subdomains" \
  -H "Authorization: Bearer ${AHREFS_API_KEY}"

Returns: Anchor text distribution with `anchor`, `backlinks`, `refdomains`.

**5. Pages by Backlinks (Best by Links)**

curl -s "https://api.ahrefs.com/v3/site-explorer/best-by-links?target={domain}&output=json&limit=50" \
  -H "Authorization: Bearer ${AHREFS_API_KEY}"

Returns: Top linked pages with `url`, `backlinks`, `refdomains`, `dofollow`.

**6. Domain Rating**

curl -s "https://api.ahrefs.com/v3/site-explorer/domain-rating?target={domain}&output=json" \
  -H "Authorization: Bearer ${AHREFS_API_KEY}"

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:

## Backlink Profile Summary: {domain}

| Metric | Value |
|--------|-------|
| Total Backlinks | {total} |
| Referring Domains | {domains_num} |
| Referring IPs | {ips_num} |
| Referring Subnets (Class C)