You switched the client from Netlify to Cloudflare.
The old CNAME is still there. It will break.
SvelteKit agencies switch deployment adapters between Vercel, Netlify, and Cloudflare Pages as client requirements evolve. Each adapter migration adds a new CNAME — and often leaves the old one in place. SvelteKit API routes on Cloudflare Workers require separate custom domain SSL configuration distinct from the Pages project. Merlonix monitors every CNAME and certificate so adapter migrations don't create silent breakage.
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- Check cadence (Agency)
- 5 min
- SSL pre-expiry alert
- 30 days
- Independent DNS resolvers
- 3
- Vendors watched
- 11
Where Svelte and SvelteKit agencies get caught out
Three failure modes specific to SvelteKit client deployments.
SvelteKit agencies switching deployment adapters across Vercel, Netlify, and Cloudflare deal with adapter migration residue, Workers API route custom domain SSL, and prerendered CDN caching that masks DNS breaks from standard uptime monitoring.
Adapter migrations leave residual CNAME records pointing at old platforms
Switching a SvelteKit client from Netlify to Cloudflare Pages adds a new CNAME but rarely removes the old Netlify CNAME — creating a dangling record
SvelteKit agencies choose deployment adapters based on project requirements: the static adapter for fully static sites, the Netlify adapter for edge functions, the Cloudflare adapter for Workers, the Vercel adapter for serverless functions. When a client's requirements change — moving from static to dynamic, or switching hosting providers for cost or performance reasons — the agency deploys with a new adapter and updates the primary domain CNAME. The old CNAME on subdomains used during the previous deployment is often left in place because it appears benign. Netlify, Vercel, and Cloudflare all eventually decommission or reassign the hostnames behind stale custom domain registrations. When that happens, the old CNAME resolves to a different tenant's site or returns an SSL certificate mismatch error.
SvelteKit API routes on Workers need separate custom domain SSL
SvelteKit applications using the Cloudflare adapter with Workers routes configure API subdomains separately from the Pages project — with independent SSL
SvelteKit agencies deploying with the Cloudflare adapter sometimes split the application: the SvelteKit frontend runs on Cloudflare Pages with a custom domain CNAME, while server-side API routes or form actions run as a separate Cloudflare Worker with its own custom domain route. The Workers custom domain configuration — api.clientdomain.com routed to a specific Worker — requires separate setup in the Cloudflare dashboard and has its own SSL provisioning tied to that route configuration. If the Worker is redeployed to a new name, the custom domain route must be re-associated. If the custom domain route is not carried over, the API subdomain stops resolving and the SvelteKit application's server-side routes fail silently. Standard uptime monitoring checking the Pages domain will not detect the API route failure.
SvelteKit prerendered routes cache SSL breaks from uptime monitors
SvelteKit sites using prerendering serve static HTML from CDN cache — masking DNS breaks from URL-based uptime monitoring for hours
SvelteKit supports prerendering specific routes to static HTML, which is then served from the CDN edge on Vercel, Netlify, or Cloudflare Pages. Prerendered routes are cached aggressively at the CDN edge. When the DNS record or CNAME pointing the client domain at the CDN breaks, prerendered routes continue to be served from cached copies at edge nodes that have not yet invalidated. Uptime monitoring tools checking the primary URL may receive cached HTML for hours after the DNS break — reporting the site as up while the underlying routing is broken and new visitors on uncached edges receive DNS resolution errors. Merlonix monitors the CNAME record directly, not the cached HTTP response, and detects the break at the DNS layer regardless of CDN cache state.
How it works
SSL and DNS monitoring across every adapter target your SvelteKit clients have ever used.
Merlonix monitors CNAME integrity and SSL health for SvelteKit Pages domains, Workers API routes, and residual records from adapter migrations — so agencies catch CNAME breakage before the old platform decommissions the hostname.
01
Add every domain — including residual records from adapter migrations
Verify ownership with a DNS TXT record on the apex domain. Legacy subdomains from previous adapter deployments are added alongside production domains. Monitoring residual records is how you catch the reassignment problem before the old platform decommissions the hostname. Under two minutes per client to get full coverage including migration residue.
02
CNAME target monitoring catches adapter migration residue
Three independent DNS resolvers check every CNAME delegation target on every monitoring interval. When an old Netlify or Vercel CNAME target stops responding correctly for the original hostname — because the platform has reassigned or decommissioned it — the CNAME target mismatch is detected before the client encounters an SSL error.
03
SSL chain validation for Pages domains and Workers API routes independently
Full SSL chain validation on every monitored domain — including SvelteKit API subdomains on Workers custom domain routes. A Workers route custom domain SSL break fires separately from the Pages domain certificate. Cloudflare Pages certificate renewals are monitored 30 days before expiry. Certificate subject mismatches from decommissioned platform hostnames are caught immediately.
04
Vendor status for Cloudflare, Netlify, and Vercel
Merlonix monitors Cloudflare, Netlify, and Vercel platform status alongside client SSL and DNS. When a Cloudflare Workers incident causes API route failures across multiple SvelteKit client portfolios, you see the vendor event correlated with client-specific alerts — distinguishing platform incidents from adapter migration residue that requires DNS cleanup.
What the numbers mean for Svelte agencies
Monitoring built for SvelteKit portfolios across multiple deployment adapters.
SvelteKit agencies switching adapters across Vercel, Netlify, and Cloudflare need SSL and DNS monitoring that covers not just the current deployment but every CNAME the client's domain has ever pointed at.
< 10 min
Time from DNS change to alert — catches adapter migration CNAME residue and Workers API route breaks before clients encounter SSL errors
30 days
SSL expiry warning lead time — covers Cloudflare Pages certificates and Workers custom domain route SSL independently
11 vendors
Upstream services monitored — Cloudflare, Netlify, and Vercel included to distinguish platform incidents from adapter migration DNS residue
200 assets
Maximum monitored domains on the Agency plan — covers production domains, API routes, and residual adapter migration CNAMEs across a full SvelteKit client roster
Pricing
Flat monthly fee. Every adapter target and API route included.
No per-domain charges. No per-adapter fees. Pick the tier that fits your SvelteKit client count and track every CNAME without billing surprises.
Starter
For individual Svelte developers managing a small client portfolio across adapters.
$29/ month
- 10 monitored assets
- 1 seat
- 15-min check cadence
- SSL + DNS + vendor monitoring
- Email + Slack alerts
Team
For SvelteKit agencies switching adapters and managing Workers API routes across multiple clients.
$79/ month
- 50 monitored assets
- 5 seats
- 10-min check cadence
- SSL + DNS + vendor monitoring
- Email + Slack alerts
Agency
For agencies with a full SvelteKit client roster across Cloudflare, Vercel, and Netlify adapters.
$199/ month
- 200 monitored assets
- 15 seats
- 5-min check cadence
- SSL + DNS + vendor monitoring
- Email + Slack alerts
Know when an old adapter CNAME breaks before the decommissioned platform reassigns the hostname.
Add your first SvelteKit client domain in under two minutes. Production domains, Workers API routes, and legacy adapter CNAMEs are covered from the same dashboard. 14-day trial, no card required.