Reselling sGTM under your agency brand is a clean way to add a measurement service without building one. The technical setup is mostly already there; what takes effort is the polish that makes it feel like your product rather than a third-party tool. Here are the six items most agencies miss.

1. Custom domain for the dashboard

Your client should manage their tagging server through a hostname that says your agency, not the underlying provider. Most reseller-friendly providers (including SprTags at the Agency tier) let you point a CNAME at the dashboard.

2. Custom domain for tagging

For each client container, set up a tagging URL on a domain controlled by the client. data.client-site.com is the standard pattern. Document the DNS instructions in a way that survives someone forwarding the email to their CTO.

3. Branded email notifications

Outage alerts, billing notifications, and weekly reports should come from your agency address, not the provider's. Set the from-address in the provider's reseller settings.

4. Documentation for clients

Write a one-page "What is server-side tagging" intro that you can hand to clients who do not know the term. The provider's docs are technically correct but are aimed at engineers; your clients are usually marketers.

A useful structure: what server-side tagging does, why we (your agency) recommend it, what the client needs to do (almost nothing), and how to get help.

5. Pricing transparency

Decide upfront whether you bundle the tagging server cost into your retainer or pass it through. Both work; the choice affects how you communicate it. Hidden mark-ups become visible eventually, and when they do, they hurt the relationship.

6. Off-boarding plan

When a client leaves, what happens to their container? The defaults vary by provider; some delete after a grace period, some keep indefinitely. Document your policy. A 30-day grace period is reasonable. Communicate it before signing.

Pricing for resellers

SprTags Agency tier ($150/month) includes whitelabel and bulk container provisioning. The pricing page has the current numbers, including the per-container overage rates that determine your margin on heavier clients.

For smaller agencies who do not need full whitelabel, the Growth tier still allows reselling at a thinner margin. The decision usually comes down to how many clients you are managing and whether your branding matters more than your margin.