PagerDuty vs StackStorm: What are the differences?

PagerDuty: Incident management with powerful visibility, reliable alerting, and improved collaboration. PagerDuty is an alarm aggregation and dispatching service for system administrators and support teams. It collects alerts from your monitoring tools, gives you an overall view of all of your monitoring alarms, and alerts an on duty engineer if there's a problem; StackStorm: Open Source IFTTT for Ops: event-driven automation, security responses, auto-remediation with workflow engine & ChatOps. StackStorm is a platform for integration and automation across services and tools. It ties together your existing infrastructure and application environment so you can more easily automate that environment -- with a particular focus on taking actions in response to events.

PagerDuty and StackStorm are primarily classified as "Monitoring Aggregation" and "Remote Server Task Execution" tools respectively.

Some of the features offered by PagerDuty are:

• Alerting that works (and wakes you up)- When your systems go down, PagerDuty will wake you up. You choose how you want to be alerted - via phone, SMS or email, to multiple numbers, with retries.
• Integrate all your existing monitoring tools- PagerDuty works great with almost all monitoring tools including: Nagios (and Icinga), Keynote, New Relic, Pingdom, Circonus, Red Gate SQL Monitor, Server Density, Zenoss, Monit, Munin, SolarWinds and many others. If it can send email, it will work with PagerDuty.
• Native apps with push notifications- iOS and Android native apps with push notifications and a cross-platform mobile website ensure you can respond to alerts wherever you are, even on the go.

On the other hand, StackStorm provides the following key features:

• Automations tie events to actions you’d like to take, using a rules engine and, if you want, comprehensive workflow. Automations are your operational patterns summarized as code.
• StackStorm automations work either by starting with your existing scripts – just add simple meta data – or by authoring the automations within StackStorm.
• Automations are the heart of StackStorm – they allow you to share operational patterns, boost productivity, and automate away the routine.

"Just works" is the primary reason why developers consider PagerDuty over the competitors, whereas "Auto-remediation" was stated as the key factor in picking StackStorm.

StackStorm is an open source tool with 3.27K GitHub stars and 435 GitHub forks. Here's a link to StackStorm's open source repository on GitHub.