We are considering Datadog, and nothing else seems to compare to them, but they seem extremely expensive. As a small startup/solo founder, did your implementation justify costs?
Also if you send custom stats to datadog such as login activity, you can use their Anomaly detection to find suspicious behavior.
Disclaimer: we use datadog at my company and have tried all the other popular options. Hands down datadog is the most feature rich and user friendly.
Just getting logging centralized alone has saved me tons of time, which is in turn more time spent on the product. I've been able to use the log parsing to setup metrics that tell me when an outside integration is acting up and isolate which paths. Take a day to really learn how their logs work and you'll be able to generate metrics / advanced event alerting in no time.
I was hesitant to pay the premium, but the peace of mind has been worth it. You can piece the same thing together with open source tooling. But then you've got another thing to manage.
- metrics system (Prometheus, InfluxDB, Graphite, etc.)
- dashboards (Grafana)
- alerts (both the metrics system and Grafana can handle this)
If you're not a big-data company, you can self-host instances of these products reliably.
Disclosure: My startup, https://HostedMetrics.com, provides turnkey hosted versions of these software packages.
I'd be happy to explain the options that are out there and provide any advice you need. Get in touch: contact info is in my profile.