How to Audit the Backlinks Your SEO Agency Built for You

Oct 29, 2026 ·Alex Mercer

You can audit your agency's link building in about two hours with Google Search Console, a backlink tool, and a spreadsheet. Export every link the agency claims to have built, then check each one for four things: is the page real and indexed, is it topically relevant, was it paid for without a disclosure attribute, and does it sit on a site that exists mainly to sell links. At OnyxRank we run this audit on inherited campaigns before touching anything else, because the answer decides whether a link program is an asset or a liability.

This matters most for ecommerce and SaaS founders who pay a retainer and receive a monthly report with a "links built" number. That number is an output, not a result. The audit below tells you what you actually bought.

Why Link Audits Matter More Than Link Counts

Google's [spam policies](https://developers.google.com/search/docs/essentials/spam-policies#link-spam) define link spam as "creating links to or from a site primarily for the purpose of manipulating search rankings." The examples include buying or selling links for ranking purposes, excessive link exchanges, and using automated programs to create links. Google says it relies on automated systems and, as needed, human review, and that violating sites may rank lower or not appear in results at all.

In December 2022, Google announced it was [using SpamBrain to neutralize the impact of unnatural links](https://developers.google.com/search/blog/2022/12/december-22-link-spam-update). The post says SpamBrain can now detect both sites buying links and sites used for the purpose of passing outgoing links. The word "neutralize" is important. In most cases the realistic outcome is not a dramatic penalty. It is that the links you paid for simply stop counting, and you have spent months of budget on nothing. A manual action is the worse but rarer outcome.

So the audit has two goals. First, find money wasted on links that carry no value. Second, find the small number of links that create real exposure.

Step 1: Build the Master List

Ask your agency for a complete list of every link built since the engagement started. A usable list has the linking URL, the target URL on your site, the anchor text, the date live, and how the link was obtained (editorial pitch, guest post, sponsored placement, directory, or other).

Then build your own list independently so you are not relying on theirs:

1. Export linking domains from Google Search Console under Links, then Top linking sites.

2. Export the full backlink list from a third party tool such as Ahrefs or Semrush.

3. Merge the two and remove links dated before the agency started.

4. Compare against the agency list. Anything on your list but not theirs deserves a question. Anything on theirs but missing from yours may be a link that was removed or never indexed.

Each tool crawls the web differently, so no single export is complete. Using two reduces the chance of missing something.

If the agency cannot or will not produce the list, treat that as the finding. Our guide on [contract clauses that determine SEO agency results](/blog/seo-agency-contract-clauses-2026) covers how to require this reporting up front.

Step 2: Check That Each Link Is Real

Open each linking page. For a campaign with fewer than 100 links, do this by hand. For larger ones, sample at least 30 percent and prioritize the highest anchor text matches.

For each page, confirm:

The page loads and the link is present in the live HTML.
The page is indexed. Search for the exact URL in Google. A page that is not indexed cannot pass value you can measure.
The link is not hidden in a footer, sidebar, or an unrelated author bio shared across hundreds of pages.
The link is not on a page with no real traffic or readership.

A caveat on traffic: Ahrefs analyzed [44,589 non branded keywords and the top 10 results for each](https://ahrefs.com/blog/links-with-traffic-study) and found that the sum of organic traffic to referring pages correlated more strongly with rankings than the count of referring pages that had traffic. Ahrefs also stresses that correlation does not prove causation. Read that as a directional hint, not a rule. A link from a page that attracts real search visitors is a better bet than a link from a page nobody visits, and you can see the difference quickly in any backlink tool.

Step 3: Score Topical Relevance

A link from a site your buyers would never read is a weak signal at best. Score each linking domain on a simple three point scale:

**2 points:** The site covers your industry or an adjacent topic and has a real editorial audience.
**1 point:** The site is general business or lifestyle content with real readers, and the article context fits.
**0 points:** The site publishes on every topic, has no visible audience, or the article was clearly written to hold the link.

Give a zero when you see these patterns: a dozen unrelated categories on the homepage, a "write for us" page that mentions pricing, articles with no byline or a generic one, and outbound links in nearly every post to unrelated commercial sites.

Add up the scores. If more than a third of your links score zero, the agency is selling volume. You will not need a spreadsheet formula to see it, because the zeros cluster on a handful of domains that appear repeatedly.

Step 4: Detect Undisclosed Paid Placements

This is the step with real risk. Google states that buying and selling links for advertising or sponsorship is not a violation when the links are qualified with a `rel="nofollow"` or `rel="sponsored"` attribute. Its documentation on [qualifying outbound links](https://developers.google.com/search/docs/crawling-indexing/qualify-outbound-links) recommends marking paid placements with `sponsored`, and notes that `nofollow` is also acceptable.

That means a paid placement is not automatically a problem. A paid placement that passes ranking credit with no qualifying attribute is the problem. Check the HTML of each link for a rel attribute. Then ask your agency directly, in writing, for each placement: was money, product, or any other consideration exchanged for this link?

Warning signs that a link was paid for, even if the agency says otherwise:

The linking site has a visible rate card or "sponsored post" page.
The same author or the same article template appears across many unrelated sites.
The anchor text is an exact match commercial keyword, such as "best project management software for agencies."
Several links went live within the same few days on sites with no obvious connection.

Document what you find. If the agency told you the links were earned through outreach and you find a rate card, you have a contract conversation to have. Our post on [vetting an AI powered link building agency](/blog/ai-powered-link-building) lists the questions to ask before signing, and the [pricing breakdown](/blog/ai-powered-link-building-pricing-2026) shows why very cheap per link pricing usually means purchased placements.

Step 5: Review Anchor Text and Target Pages

Pull the anchor text distribution. Natural link profiles are dominated by brand name, URL, and generic anchors like "this article" or "their report." If a large share of your anchors are exact match commercial phrases, that pattern looks engineered.

Also check where the links point. A healthy program sends links to pages that deserve them: original research, tools, guides, and product pages with substance. If every link points to one service or category page, ask why. That concentration is both a spam signal and a sign the agency did not produce a linkable asset.

Step 6: Decide What to Do With the Results

Sort every link into one of three buckets.

**Keep.** Real page, indexed, relevant, properly attributed. Do nothing.

**Ignore.** Low value but harmless, such as a stray directory listing. Google's own wording suggests such links are mostly neutralized, so spending effort removing them is rarely worth it.

**Act.** Clearly paid links without attributes, or links from networks that exist to pass links. Ask the agency to have the publisher add `rel="sponsored"` or remove the link. If you ever receive a manual action for unnatural links, the Manual actions report and Search Console message center are where Google notifies you, and a reconsideration request is the path to appeal. Do not file one preemptively.

Then act on the commercial side. Compute the cost per link that scored 1 or 2 and survived the audit. If your retainer includes $2,000 a month for link building and only four links a quarter passed, you can see the real price of each useful link and decide whether to renegotiate, replace the agency, or move that budget into content that earns links on its own.

What a Good Link Report Looks Like

When you ask for reporting going forward, request these fields for every placement: linking URL, date live, how it was obtained, whether anything was paid, the rel attribute, the target page, and the anchor text. A program that earns links through original data and real outreach can produce that table without effort. A program that buys links tends to resist it.

FAQ

How often should I audit my agency's backlinks?

Quarterly is enough for most businesses. Run the full audit at contract renewal and a lighter check each quarter that looks only at new links.

Is buying links ever acceptable?

Google says buying and selling links for advertising or sponsorship is not a violation when the links are qualified with `nofollow` or `sponsored`. Paid links meant to pass ranking credit without that qualification fall under link spam.

Will bad links get my site penalized?

Google says SpamBrain is designed to neutralize unnatural links, which usually means they are ignored. Penalties through manual actions exist but the more common cost is wasted budget. Your Search Console Manual actions report will show if a penalty applies.

Do I need to disavow links the agency built?

Not by default. Start by asking the publisher to add a qualifying attribute or remove the link. Disavowing is a last resort for clear, unfixable problems, and it should not be used for ordinary low value links.

What if the agency refuses to share the link list?

Treat that as a material finding. You are paying for work product, and you should be able to see it. Review the contract and consider whether this is a provider you want to keep.

Key Takeaways

Build your own link list from Search Console and a backlink tool. Do not rely on the agency's report alone.
Verify that each link is live, indexed, and on a page with real readers.
Score relevance. A cluster of zero scores on repeat domains signals volume selling.
Check rel attributes. Paid links need `sponsored` or `nofollow` to stay within Google's policy.
Calculate the cost per surviving link and use it in your renewal decision.

If you would rather have a second set of eyes on a link profile, [request a free SEO audit from OnyxRank](/free-audit) and we will review your backlinks and tell you what is worth keeping. You can also see how we structure link programs on our [pricing page](/pricing).