I thought uptime monitoring was solved. Then I started building one.
When an agency client says:
“The site feels slow.”
That’s usually the beginning of a very painful conversation.
Because by the time users notice:
- leads may already be dropping
- conversions may already be affected
- support tickets may already be coming in
- the client may already think nobody was watching
That’s the part of monitoring I underestimated when I started building Sentinel.
I thought uptime monitoring was mostly about detecting outages.
But agencies deal with a different problem:
sites that are technically “up,” while the experience is already degrading.
A site can still return 200 OK while:
- DNS resolution slows down
- TLS negotiation starts failing intermittently
- TTFB spikes in one region
- a CDN edge behaves differently geographically
- third-party scripts delay rendering
- content partially fails to load
From the outside, the system looks healthy.
But the client experience isn’t.
One thing that changed my perspective recently was breaking response timing into phases instead of treating performance as a single number.
I started separately tracking:
- DNS lookup time
- TCP connection time
- TLS handshake time
- time to first byte
That exposed patterns I never would’ve seen from “response time” alone.
Sometimes the earliest warning sign isn’t downtime.
It’s friction.
And for agencies managing dozens of client sites, catching that degradation before the client notices is where monitoring becomes genuinely valuable.
The gap you're describing is exactly what I kept hitting too — uptime monitoring tells you the service is up, but not whether the output was actually correct.
I ended up going a layer deeper: monitoring for automation workflows specifically (n8n, Zapier, Make, AI agents). The "it ran successfully but produced wrong data" case is what none of the existing tools catch.
Curious what angle you're taking on it — infrastructure level or output validation?
Right now I’m much more focused on the infrastructure/degradation side.
Things like detecting:
I do think the output validation/workflow side is really interesting though, especially as more businesses depend on automation and AI systems.
This is a really smart angle. Most uptime monitoring solves for 'is it offline?' But the real pain (especially for agencies) is 'is it slow and making my client angry?' That's a completely different problem.
The phase breakdown — DNS, TCP, TLS, TTFB — that's the kind of detail most tools hide behind a single 'response time' number. Makes sense that it exposes patterns you'd otherwise miss.
Quick question — for an agency with 50+ client sites, how do you surface this without drowning them in alerts? Do you have a 'only alert if degradation is noticeable to real users' kind of logic?
I'm building Bexra — Helping entrepreneurs find, build & grow. Not related, but your point about 'catching the problem before the customer notices' applies to a lot of things, not just monitoring. Thanks for sharing
Right now I’m handling it pretty conservatively to avoid alert fatigue.
Actual downtime alerts only trigger when the site is down across all monitoring regions.
The degradation/performance side is surfaced more as visibility and troubleshooting data than immediate paging, coupled with fairly fine-grained notification controls so agencies can decide how noisy they want things to be.
As I add more regions/servers, I’ll probably move toward a percentage-based approach instead of strict all-regions-down logic.
That’s part of why I started breaking response timing into phases. It helps expose patterns and regional issues without turning every slowdown into an alert storm.
Very true. “Up” does not always mean users are having a good experience. Breaking response timing into separate phases gives much better visibility
Exactly. Breaking requests into phases makes it much easier to see where things are actually slowing down.
I learned this the hard way too — “site is up” and “site feels fine” are completely different things.
Breaking timing into DNS, TLS, TTFB, etc. gives way better early warnings before clients start complaining.
That's usually how it goes though - you don't really see the gaps until you're deep in the weeds building it yourself. What made you finally pull the trigger on it?
Honestly, I just started building it for fun, then completely went down the rabbit hole.
The deeper I got into monitoring, the more I realized how many edge cases and workflow gaps agencies were dealing with by stitching together multiple tools and internal systems.
That’s when it started feeling less like a side project and more like a real product opportunity.
That’s the real wedge.
Most monitoring tools are still selling uptime to technical buyers.
Agencies are buying client trust.
That’s a very different product.
The useful signal here is not “did the site go down.”
It’s “did the client notice before we did.”
That is the actual failure event agencies pay to avoid.
Once you frame it that way, Sentinel stops looking like another uptime tool and starts looking more like client-facing risk infrastructure.
That positioning likely matters more than the feature list.
Also worth watching:
“Sentinel” is familiar enough to explain the category, but generic enough that it may cap how proprietary the product feels if this expands past agency monitoring.
Exirra.com would carry more weight if you push this further into trust / performance infrastructure.
Exactly.
“Did the client notice first?” is starting to feel like the metric that actually matters.
A lot of agencies already have uptime monitoring somewhere in their stack.
What they really care about is reducing the chances of painful client conversations.
That framing changed how I think about the product quite a bit.
Exactly.
And once that becomes the metric, the product is no longer just monitoring uptime.
It is protecting the agency from trust damage.
That is a much stronger category.
The only reason I pushed on the name is because “Sentinel” still sounds like a general monitoring/security label.
Useful, but familiar.
If the real promise is:
“we catch client-facing failures before your client does”
then the brand should probably feel more proprietary than another monitoring tool.
That is where the trust infrastructure angle gets much bigger than uptime.
Truth be told, it actually started as a pretty general monitoring tool, and in a lot of ways it still is.
But the deeper I got into it, the more agency-specific patterns and workflows started influencing the architecture and product decisions.
Adam, one follow-up because this thread stuck with me.
The key point was that Sentinel may have started as general monitoring, but the product decisions were already being shaped by agency-specific workflows.
That is usually where the category decision becomes important.
If the buyer is an agency, the product is not really selling “uptime monitoring.” It is selling protection from client-facing trust damage: catching failures before the client notices, reducing awkward client conversations, and making the agency look more proactive.
That is a much sharper product than a general monitoring tool, but the name, landing page, and category frame need to make that obvious quickly.
I’m doing a few focused naming/positioning audits for early products now. For Sentinel, I’d specifically look at whether the current name and copy are still framing it as generic monitoring, or whether it can clearly own the “agency trust infrastructure” angle.
Not a long consulting thing. Just a sharp written breakdown covering current name risk, category frame, buyer perception, domain/name ceiling, and the strongest positioning direction before more product and landing-page decisions harden.
I’m keeping the first few at $99 while refining the format.
If useful, connect here and I can give Sentinel a clear outside read:
https://www.linkedin.com/in/aryan-y-0163b0278/
That’s usually the inflection point.
The product may have started general, but if the architecture is already being shaped by agency-specific workflows, the category is shifting whether the name has caught up or not.
That’s where generic monitoring names start becoming a ceiling.
If Sentinel stays broad, people will keep comparing it to uptime tools.
If the product is really becoming agency trust infrastructure, the name and positioning need to make that shift obvious faster.
Otherwise the product evolves, but the market keeps filing it in the old category.