Link building for an agency means earning links for several client sites at once without tying them together. Get written client consent for every tactic, never cross-link clients or require footer credit links (Google's spam policies name both), vary sources so no two clients share a footprint, and report referring domains and traffic, not link counts.
You run a small agency with eight retainer clients. Each contract promises "monthly link building", the cheapest way to deliver it is the same list of guest post sites for everyone, and the web design side of the business has been adding "Website by" links to every client footer for years. One client asks why their new links all come from sites that also link to your other clients. That question is where agency link building usually goes wrong.
Why link building is different for an agency
An agency builds links for sites it does not own, for clients who carry the risk, at a scale where shortcuts repeat across every account.
The client owns the risk
If a tactic triggers a manual action, it lands on the client's domain, not yours. That makes consent a practical issue as well as an ethical one: the client needs to know what you are doing on their behalf before you do it.
Shortcuts repeat across every client
One freelancer buying a few links leaves a small trail. An agency buying from the same vendor for 20 clients creates a pattern: the same sites, the same anchor styles, the same month. If that vendor's network gets devalued, every client loses at once.
Clients judge by the monthly report
The incentive pushes toward volume: a report with 10 new links looks better than one with 2, even when the 2 are worth more.
What Google says about agency-specific tactics
Google's spam policies on link spam list several practices that mostly happen at agencies, because agencies control many sites at once.
Footer credit links on client sites
The policy names "widely distributed links in the footers or templates of various sites" as link spam. A "Website by Agency" link on 50 client footers is exactly that pattern. If you keep the credit for branding, add rel="nofollow" so it passes no ranking credit. Our page on footer and sidebar links explains why these links are discounted anyway.
Links written into the contract
The same list includes "requiring a link as part of a Terms of Service, contract, or similar arrangement". A clause that obliges clients to link back to the agency belongs in that category. Remove it from your contract template.
Cross-linking your client portfolio
"Excessive link exchanges" and "partner pages exclusively for the sake of cross-linking" are also named. Linking client A to client B because both pay you is a private network with extra steps. Our explainer on what a PBN is covers how Google spots them. A genuine link between two clients is fine when one would link to the other anyway, for example a caterer and a venue that really work together.
How to avoid a footprint across client sites
A footprint is anything that makes your clients' links look like they came from one operator. The fix is to make each client's link sources look like that client's own industry.
Build each client's list from their niche
Start from the sites that link to the client's competitors, not from your agency's standing list of "sites we use". A dental clinic and a SaaS tool should have almost no linking domains in common.
Cap how often you reuse a site
Set a simple rule, for example no more than one client per linking site per year. Keep a shared spreadsheet of every placement so the account managers can see it before they pitch.
Vary the anchor text and timing
Ten clients all gaining exact-match anchors on the first of the month is a visible pattern. Let each client's anchors follow what is natural for their brand, mostly branded and plain URLs. See what a healthy anchor text ratio looks like.
Getting client consent in writing
Consent protects the client and protects you when a tactic goes wrong. Write it down before the first link.
What to put in the agreement
List the tactics you will use (digital PR, guest posts, link exchanges, resource page outreach) and the ones you will not (paid links that pass ranking credit, PBNs, bulk directories). Say whether the client's staff will be quoted or named in outreach, and who approves content published under their brand.
Who publishes on the client's own site
Link exchanges and guest contributions often require the client to publish something in return. Agree who writes it, who approves it and how links on the client's own blog will be chosen.
How to report link building to clients
Report what the client can verify and what moves their business, not a raw count of new links.
Metrics worth reporting
New referring domains (not total links), the pages each link points to, whether each link is still live, and changes in organic clicks to those pages in Google Search Console. A link from a site the client's customers actually read deserves a line of its own.
Set realistic expectations on volume
Cold outreach is slow even when it is done well. Backlinko's study of 12 million outreach emails found that only 8.5% got any reply. A retainer that promises 20 editorial links a month for a small budget is promising something outreach rarely delivers, which is how agencies end up buying links to hit the number.
Where link exchanges fit for agencies
A relevant one-for-one swap between a client and an unrelated third party is an ordinary editorial link, as long as the client approves it and the volume stays modest. The difference from cross-linking is that the partner is a real site in the client's market, not another account on your books. On Backlinkster, every submitted link must be an article on the member's own domain and each swap is verified by API, so a client can see exactly where each link sits. See how swaps work.
Frequently asked questions
Is it OK for an agency to put a link in every client's footer?
Only with rel="nofollow". Google's spam policies name "widely distributed links in the footers or templates of various sites" as link spam, so a followed credit link across all client sites is a risk to every one of them.
Can an agency link its clients to each other?
Only where the link would exist anyway because the businesses genuinely work together. Linking clients to each other because they share an agency is a link scheme, and Google lists partner pages made "exclusively for the sake of cross-linking" as spam.
How many links should an agency build per client per month?
There is no safe or standard number. Base it on the gap between the client's referring domains and those of the pages ranking above them, and on what outreach can realistically deliver at the budget, since most outreach emails get no reply.
Should agencies tell clients which tactics they use?
Yes. The client carries the risk if a tactic leads to a manual action, so list the tactics in the agreement and show every placement in the report.
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