React SPAs load from the CDN.
API subdomains break silently when DNS drifts.
React agencies deploy client SPAs to CDN platforms with custom domain CNAME delegations — and configure separate API subdomains for backend services. The SPA frontend loads correctly from CDN cache long after its DNS record breaks. The API subdomain that the SPA depends on breaks first and fails silently. Merlonix monitors both layers so you know before the client does.
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- Check cadence (Agency)
- 5 min
- SSL pre-expiry alert
- 30 days
- Independent DNS resolvers
- 3
- Vendors watched
- 11
Where React agencies get caught out
Three failure modes specific to React SPA client deployments.
React agencies managing client SPAs across multiple hosting platforms deal with API subdomain SSL, multi-platform CNAME configurations, and CDN caching that masks DNS breaks from standard uptime monitoring.
API subdomain SSL breaks independently
React SPA API subdomains have independent SSL that expires and breaks separately from the frontend
React agencies configure client API subdomains — api.clientdomain.com or services.clientdomain.com — pointing to backend services on AWS, Azure, or a VPS. These API subdomains have their own SSL certificates, issued against their own CNAME records, separate from the frontend CDN deployment. When a client nameserver migration drops the API subdomain CNAME, the frontend SPA continues loading from CDN cache while all API calls fail with SSL or DNS errors. The symptom from the client's perspective is "the site loads but nothing works" — which is harder to diagnose and more disruptive than a total outage.
Multi-platform hosting complexity
React agencies deploying across Vercel, Netlify, and AWS Amplify have no unified DNS view
React agency portfolios rarely standardize on one hosting platform. Some clients are on Vercel because that's where their previous developer set them up. Others are on Netlify. Enterprise clients may be on AWS Amplify or Azure Static Web Apps with their own CNAME configuration format. Each platform uses different CNAME target syntax, different custom domain validation approaches, and different certificate provisioning timelines. Managing CNAME integrity across three hosting platforms with different configuration patterns requires three dashboards and manual cross-referencing. Merlonix provides one view across all platforms.
SPA caching masks DNS breaks
CDN-cached SPAs continue loading correctly for hours after the underlying DNS record breaks
React SPAs served from CDN edges are aggressively cached — the JavaScript bundle, HTML shell, and static assets are distributed across CDN nodes globally. When the DNS record pointing the client's custom domain at the CDN breaks, requests routed through nodes with warm caches continue to succeed for hours or days. The break propagates gradually as cache entries expire. Standard uptime monitoring checking the production URL may show the site as "up" for the entire warm-cache window while the DNS record has been broken for hours. Merlonix monitors the CNAME record directly — the break is detected within minutes of the DNS change, regardless of cache state.
How it works
SSL and DNS monitoring across every platform your React clients use.
Merlonix monitors CNAME integrity and SSL health for React SPA frontends and API subdomains from a single dashboard — so agencies get coverage across Vercel, Netlify, and AWS Amplify without switching between platforms.
01
Add frontend and API subdomains per client
Verify ownership with a DNS TXT record on the apex domain. Frontend CDN domains and API subdomains are added without additional verification. Under two minutes per client — both layers monitored from the same dashboard, regardless of which hosting platform each uses.
02
CNAME integrity checks for all hosting platforms
Three independent DNS resolvers check every CNAME delegation on every monitoring interval — whether the target is Vercel, Netlify, AWS Amplify, or a direct API server CNAME. When a client DNS migration drops an API subdomain CNAME, the alert fires within minutes, before the SPA starts returning data errors to end users.
03
SSL monitoring for both frontend and API subdomains
Full SSL chain validation on both the frontend CDN domain and all API subdomains independently. An API subdomain certificate expiry fires 30 days in advance — separate from the frontend certificate. Domain registration expiry is tracked separately from SSL expiry.
04
Vendor status for Vercel, Netlify, and AWS
Merlonix monitors Vercel, Netlify, and Cloudflare platform status alongside client SSL and DNS. When a Vercel edge incident causes SPA loading failures across multiple client portfolios, you see the vendor event before clients report it.
What the numbers mean for React agencies
Monitoring built for multi-platform React SPA portfolios.
React agencies managing client portfolios across Vercel, Netlify, and AWS Amplify need CNAME and SSL monitoring that covers both the CDN frontend and the API subdomains — and catches breaks before CDN caching hides them.
< 10 min
Time from DNS change to alert — catches CNAME drift before CDN cache masks the break from standard uptime monitoring
30 days
SSL expiry warning lead time — covers both frontend CDN certificates and API subdomain certificates independently
11 vendors
Upstream services monitored — Vercel, Netlify, and Cloudflare included for cross-client incident correlation on React portfolios
200 assets
Maximum monitored domains on the Agency plan — covers frontend and API subdomains across a full React SPA client roster
Pricing
Flat monthly fee. Every domain and hosting platform included.
No per-domain charges. No per-platform fees. Pick the tier that fits your React client count and add clients without billing surprises.
Starter
For individual React developers managing a small SPA client portfolio.
$29/ month
- 10 monitored assets
- 1 seat
- 15-min check cadence
- SSL + DNS + vendor monitoring
- Email + Slack alerts
Team
For React agencies with frontend and API subdomains across multiple hosting platforms.
$79/ month
- 50 monitored assets
- 5 seats
- 10-min check cadence
- SSL + DNS + vendor monitoring
- Email + Slack alerts
Agency
For agencies with a full React SPA client roster across Vercel, Netlify, and AWS Amplify.
$199/ month
- 200 monitored assets
- 15 seats
- 5-min check cadence
- SSL + DNS + vendor monitoring
- Email + Slack alerts
Know when an API subdomain breaks before the SPA stops working.
Add your first React client domain in under two minutes. Frontend and API subdomains are covered from the same dashboard. 14-day trial, no card required.