Merlonix vs Oh Dear for Agencies: Developer-First Monitoring vs. Agency Portfolio Monitoring

Oh Dear is one of the most technically comprehensive monitoring tools available in the mid-market. Beyond basic uptime, it monitors broken links, mixed content, DNS records, SSL certificates, performance scores (via Lighthouse), cron job health, and sitemap validity. The API is clean, the notification system is flexible, and the product has a strong reputation in the Laravel and PHP developer community where it originated.

Agencies that reach for Oh Dear are often coming from UptimeRobot or Better Uptime and want more check depth — specifically the SSL and DNS coverage that simpler tools lack. Oh Dear delivers on that depth. The limits that emerge for agency use are architectural and economic rather than feature-based: the tool is designed for a developer monitoring their own properties, and that design assumption shows when you try to use it to manage portfolios for paying clients.

What Oh Dear Gets Right

Check Breadth

Oh Dear covers more check types out of the box than most monitoring tools:

Uptime: HTTP/HTTPS checks with configurable thresholds
SSL: Certificate validity, expiry date, chain completeness, and cipher suite issues
DNS: Nameserver changes, A/AAAA/MX/CNAME record drift
Domain registration: Expiry date monitoring independently from certificate expiry
Broken links: Crawl-based detection of 404s and broken internal/external links
Mixed content: Detection of HTTP resources loaded on HTTPS pages
Performance: Lighthouse score monitoring with alerting on score drops
Cron jobs: Heartbeat monitoring for scheduled tasks
Sitemap: Validation that sitemap.xml is present and parseable

For a developer managing their own application infrastructure, this is a genuinely powerful stack. SSL, DNS, and domain registration monitoring together is a level of coverage that most tools do not provide as an integrated set.

Certificate Chain Depth

Oh Dear's SSL monitoring goes beyond expiry dates. It validates the full certificate chain, flags cipher suite issues, and reports on certificate details that affect browser trust. This depth of SSL inspection is uncommon and genuinely useful for agency use cases where certificate chain errors cause client incidents.

Clean API

Oh Dear's API is well-documented and RESTful. For agencies that want to pull monitoring data into their own dashboards or automate onboarding workflows, the API is a practical tool.

No-Agent Architecture

Oh Dear monitors from external check nodes — no agents installed on client servers, no code deployed. This is the correct model for agency monitoring where you do not have server access to most client environments.

Where Oh Dear Breaks Down for Agencies

Single-Owner Architecture

Oh Dear's data model is built for a single account owner monitoring their own sites. Every site in Oh Dear belongs to a single account. There is no client account concept, no structural separation between "Client A's sites" and "Client B's sites," and no client-level permission model that lets you give Client A access to their monitoring data without giving them access to Client B's.

Agencies work with clients who sometimes want to see their own monitoring data — their certificate status, their uptime history, their DNS records. In Oh Dear, the only way to do this is to create a separate Oh Dear account per client, which multiplies the tool cost and the management overhead. Or you share a view of your account, which exposes all client data.

This is not an oversight — it reflects the product's design assumption that you are monitoring your own properties. Adapting it to a multi-client agency model requires workarounds that the architecture does not support cleanly.

Per-Site Pricing at Portfolio Scale

Oh Dear's pricing is based on the number of sites monitored. At small portfolio sizes, this is competitive. At agency scale — 20 clients with 5 domains each is 100 sites — the pricing model has different economics than a per-client pricing model.

The asymmetry is: an agency charges clients per client relationship, not per domain. A client paying $199/month generates the same revenue whether they have 3 domains or 10. But Oh Dear's cost grows linearly with domain count. An agency managing 10 domains per client at scale pays significantly more per client relationship than one whose clients have fewer domains, regardless of what either client pays.

Per-client pricing (where the cost scales with the agency's client count, not the per-client domain count) aligns better with how agencies are structured commercially.

No Vendor Status Monitoring

Oh Dear's check suite does not include vendor status monitoring — tracking the operational health of third-party platforms that clients depend on (Shopify, Stripe, HubSpot, Mailchimp, cloud providers). When a vendor has an outage and a client's site breaks, the agency's monitoring shows the symptom (failed uptime check) but not the cause (vendor incident).

Correlating vendor status with client-side symptoms is a category Oh Dear does not address. For agencies who find themselves spending diagnostic time on vendor incidents before identifying the root cause, this gap is a regular operational cost.

No Brand Asset Attestation

Oh Dear's check types are technical: uptime, links, performance, certificates. It does not provide any mechanism for certificate-based brand asset attestation — the documented delivery record for logos, domain configurations, and brand assets that agencies with IP-sensitive clients need to maintain.

For agencies in trademark-heavy categories or whose clients have had IP disputes, the monitoring stack needs to produce attestation records as a by-product of normal delivery. This is not a monitoring feature Oh Dear addresses.

Reports Are Technical, Not Client-Facing

Oh Dear provides per-site dashboards and alert histories. These are useful for internal technical review but are not formatted for client delivery. A monthly monitoring report for a client on retainer — showing what was checked, what was caught, what the certificate and domain status looks like going into next month — requires extracting Oh Dear's data and reformatting it manually.

At one or two clients, this is a minor task. At a portfolio, it is a recurring overhead that needs to be scheduled and tracked.

The Transition Point

Agencies using Oh Dear typically move when one of three things happens:

Client count makes the single-account model untenable. Once the agency needs to give individual clients access to their own monitoring data, or once the per-site pricing grows faster than per-client revenue, the economics of Oh Dear's architecture shift unfavourably.
Monthly reporting becomes a visible cost. Oh Dear's data is useful internally but does not translate to client-deliverable reports without manual work. At portfolio scale, this manual work is a recurring cost that compounds monthly.
The agency wants vendor correlation. Oh Dear's technical depth is strong within the site-based check model but does not cover the vendor status correlation that agencies managing third-party-dependent client stacks need for fast incident diagnosis.

Agencies that primarily manage their own applications, or use monitoring for internal technical health tracking rather than client retainer delivery, often stay on Oh Dear. The transition happens when the agency's monitoring need is fundamentally about managing client relationships at scale.

What Merlonix Provides Instead

Merlonix is built for the multi-client agency use case:

Client-level architecture: Clients are the primary structural unit. Each client has its own scope, alert configuration, and reporting view. Client-level access controls let clients view their own data without accessing other clients'.

Per-client pricing: Costs scale with client relationships, not domain count. An agency charging $199/month per client pays predictably regardless of how many domains that client has.

SSL and DNS depth: Certificate chain validation, DNS integrity monitoring, domain registration expiry, and vendor status correlation — the full signal stack with unified alerting.

Client-facing report output: Monthly reports formatted for client delivery. No data extraction or reformatting required.

Brand asset attestation: Certificate-based documentation of delivered brand assets for clients with compliance or IP protection requirements.

Agencies moving from Oh Dear for client portfolio use typically retain Oh Dear for monitoring their own applications (where its technical depth and developer API are genuine strengths) and use Merlonix for client-facing monitoring retainers.

→ Complete guide: SSL Monitoring Buyer's Guide for Agencies: What the Category Actually Covers
→ See also: Best SSL Monitoring Tools for Agencies: What to Look for When Managing Client Portfolios
→ See also: Merlonix vs Freshping for Agencies: Free Uptime Monitoring vs. Client Portfolio Monitoring
→ See also: Merlonix vs Better Uptime for Agencies: On-Call Workflows vs. Client Portfolio Monitoring