How to Add Security Monitoring to Your Agency Retainer

Most web agencies leave money on the table when it comes to retainers. You ship a beautiful site, hand over the keys, and then bill a few hours a month for content tweaks and the occasional plugin update. Meanwhile, your client's SSL certificate is six weeks from expiry, their security headers are missing, and a misconfigured CORS policy is quietly leaking data.

Security monitoring is one of the easiest, highest-margin services you can add to an existing retainer. It's measurable, it's recurring, and clients understand why it matters. This guide walks through exactly how to package, price, and deliver it.

Why Security Monitoring Belongs in Every Retainer

Websites aren't static. Browsers deprecate ciphers, certificates expire, dependencies introduce vulnerabilities, and DNS records drift. A site that scored an A on launch day can quietly slip to a D within a year if no one is watching.

Adding monitoring to your retainer benefits both sides:

• For the client: peace of mind, compliance evidence (PCI, ISO 27001, SOC 2), and protection against reputational damage.
• For the agency: predictable monthly revenue, justification for higher retainer fees, and early warning of issues before they become emergencies.

Step 1: Define the Scope of Monitoring

Before you write a proposal, decide exactly what you'll monitor. Vague promises like "we'll keep your site secure" lead to scope creep and unhappy clients. Be specific.

Core checks to include

• SSL/TLS: certificate expiry, protocol versions (TLS 1.2+), cipher strength, and chain validity.
• Security headers: Strict-Transport-Security, X-Content-Type-Options, X-Frame-Options, Referrer-Policy, Permissions-Policy.
• Content Security Policy: presence, strictness, and unsafe directives like unsafe-inline.
• Cookies: Secure, HttpOnly, and SameSite flags on every cookie.
• DNS: SPF, DKIM, DMARC, CAA records, and DNSSEC where applicable.
• CORS: overly permissive Access-Control-Allow-Origin values.
• Mixed content and outdated libraries on the front end.

Optional add-ons for premium tiers

• Uptime and performance monitoring
• Malware scanning
• WordPress or CMS-specific vulnerability checks
• Penetration testing once or twice a year

Step 2: Pick Your Tooling

You don't need to build this yourself. The right tool gives you a clear grade, an actionable report, and an API or PDF export you can share with clients.

WebSentry is built specifically for this use case: it scans a domain and returns an A–F grade across SSL, headers, CSP, cookies, DNS, and CORS, with prioritised fixes. For an agency, that means you can run a scan in 30 seconds, drop the report into a client email, and immediately have a talking point for the retainer call.

Whatever tool you pick, look for:

1. A clear letter or numeric grade clients can understand at a glance
2. Specific, actionable remediation steps (not just "header missing")
3. The ability to scan multiple domains and export reports
4. Alerting when scores drop or certificates approach expiry

Step 3: Productise the Offer

Don't sell hours, sell outcomes. Package security monitoring into named tiers so clients can self-select.

Example tiered structure

• Essentials ($75–$150/month): monthly automated scan, quarterly summary report, certificate expiry alerts.
• Standard ($200–$400/month): weekly scans, monthly report with remediation, two hours of fix time included.
• Premium ($500–$1000/month): daily monitoring, real-time alerts, unlimited remediation within reason, annual penetration test.

If you already have a retainer in place, add a security line item rather than rebuilding the whole agreement. A simple amendment like "Security Monitoring — $150/month, includes monthly scan and up to 1 hour remediation" is enough.

Step 4: Write the Retainer Clauses

Your contract should clarify what's included, what isn't, and what happens when something goes wrong. Sample clauses to adapt:

• Scope: "Monitoring covers the primary domain and up to three subdomains. Additional domains charged at $25/month each."
• Reporting: "A summary report will be delivered by the 5th of each month."
• Response times: "Critical issues (expired certificate, exposed credentials) addressed within 4 business hours. High-severity issues within 2 business days."
• Exclusions: "Monitoring does not include third-party services, payment gateways, or infrastructure outside the agency's control."
• Liability: make clear that monitoring reduces but does not eliminate risk.

Step 5: Onboard the Client

The first 30 days set the tone. Run a baseline scan, walk the client through the findings, and fix the low-hanging issues immediately. This proves value before the second invoice lands.

1. Run an initial WebSentry scan and save the report as the baseline.
2. Schedule a 30-minute review call. Walk through the grade and the top three risks.
3. Fix anything quick (missing headers, weak cookie flags) within the first week.
4. Set up recurring scans and certificate expiry alerts.
5. Add the next scan date to a shared calendar so the client sees the work happening.

Step 6: Communicate Value Every Month

The biggest reason clients churn from retainers is invisible work. Security monitoring is especially prone to this — if nothing breaks, the client wonders what they're paying for.

Counter this with a short monthly report. It doesn't need to be long; one page is plenty:

• Current security grade and trend over the last three months
• Issues detected and resolved this period
• Upcoming concerns (cert expiring in 45 days, new CSP recommendations)
• One "did you know" educational tip relevant to their stack

Tip: turn incidents into proof of value

When you catch something — an expiring cert, a cookie flag missing after a deploy, a new mixed-content warning — tell the client. A short Slack message saying "Caught and fixed before it hit production" is worth more than any report.

Common Mistakes to Avoid

• Promising 100% security. You can't, and you shouldn't try.
• Bundling monitoring into hosting fees. Separate the line items so clients see what they're paying for.
• Manual-only scanning. If you rely on memory, you'll miss things. Automate the scans, even if remediation stays manual.
• No upgrade path. Build tiers so growing clients have somewhere to go.

Wrapping Up

Security monitoring is one of the rare retainer add-ons that's easy to sell, easy to deliver, and genuinely valuable to the client. Define a clear scope, use a tool that gives you fast, credible reports, productise it into tiers, and communicate the work every single month.

If you want a quick way to see what a baseline report looks like, run a free scan on any client domain at websentry.dev. You'll get an A–F grade and a prioritised list of fixes in under a minute — exactly the kind of artefact that turns a security conversation into a signed retainer.