what should I use for kill switches and staged rollouts

For kill switches and staged rollouts, the best choice is usually a feature flag / feature management system.

Good options

• LaunchDarkly — very strong for kill switches, gradual rollouts, targeting, and experimentation
• Unleash — solid open-source option, good for self-hosting
• Split — strong rollout and experimentation platform
• Firebase Remote Config — lightweight option, especially for mobile apps
• Homegrown config flags — okay for very simple needs, but harder to manage safely at scale

What to look for

For your use case, make sure the system supports:

• Instant disable / kill switch
• Percentage-based rollouts like 1%, 5%, 25%, 50%, 100%
• Targeting by user, org, region, app version
• Audit logs
• Central control without redeploying
• Fast propagation / low latency

Practical recommendation

• If you want best-in-class and don’t mind paying: LaunchDarkly
• If you want open source / self-hosted: Unleash
• If you only need simple mobile or config-driven toggles: Firebase Remote Config

Common pattern

Use it for:

• turning features off quickly if something breaks
• enabling a feature for internal users first
• rolling out to a small cohort before full release

If you want, I can also recommend the best option based on your stack, like backend-only, mobile, React, Kubernetes, or microservices.