Scaling On-Call at Startups

The On-Call Scaling Journey

Every successful startup faces the same progression: what starts as a founder carrying a phone eventually needs to become formalized engineering rotations. But the transition is rarely smooth. Try to implement enterprise-grade on-call too early and you add unnecessary process overhead. Wait too long and you risk burning out your early engineers or creating ad-hoc patterns that don’t scale.

Industry research shows that approximately 70 percent of startups fail at the scaling stage—often because infrastructure practices that worked at 5 engineers break down completely at 20. On-call is one of those practices that requires deliberate evolution as team size and system complexity grow.

This guide walks through the distinct phases of on-call scaling at startups, identifying the specific transitions that matter and the practices that enable sustainable growth.

Stage One: 1-5 Engineers

In the earliest stage, formality feels like overkill. The founder or CTO handles most operational issues. Maybe one or two engineers share informal coverage. Nobody uses scheduling tools—coordination happens via Slack or shared understanding.

This approach works temporarily, but creates problems quickly. Founders become bottlenecks for operational knowledge. Engineers never develop response skills. Alerts get missed because nobody feels clearly responsible.

What to Implement

Even with tiny teams, establish basic foundations:

Documented expectations: Write down response time requirements and escalation paths. Who handles what types of alerts? How quickly should someone acknowledge? What constitutes an emergency requiring immediate wake-up versus something that can wait until morning?

Basic rotation: If you have three to five engineers, implement weekly rotation where one person owns primary response. This forces knowledge distribution and prevents founder dependency.

Alert discipline: Resist the temptation to alert on everything. Critical infrastructure failing warrants immediate notification. Minor warnings do not. Startups that establish alert quality early avoid the technical debt of noisy monitoring that plagues larger organizations.

Founders should participate in early rotations. This achieves two goals: it demonstrates that on-call is valued work deserving leadership involvement, and it ensures founders directly experience pain points that need fixing.

Stage Two: 5-10 Engineers

This transition marks the shift from informal to formal on-call. You now have enough engineers to implement real rotations but not enough to handle complexity poorly. Get the foundations right here or face painful refactoring later.

Critical Transitions

Implement scheduling tools: Spreadsheets and shared calendars break down at this scale. You need automated rotation scheduling with timezone support and exclusion management. When engineers take vacation, the system should automatically advance to the next available person without manual coordination.

Tools like Upstat provide weekly rotation algorithms that space assignments evenly across team members, timezone handling using IANA timezone databases, and user-specific exclusions for vacation management—all essential capabilities at this stage.

Establish primary and secondary coverage: Single points of failure defeat the purpose of on-call systems. Configure shifts with two concurrent users: primary handles initial response, secondary provides escalation backup. This prevents situations where one engineer struggles alone with problems beyond their expertise.

Document everything: Your early engineers hold operational knowledge in their heads. As you add new team members, tribal knowledge becomes a scaling bottleneck. Create runbooks for common incidents, document system architecture, and establish playbooks for frequent response patterns.

Watch For

The most dangerous pattern at this stage: routing incidents around the rotation to experienced engineers. This burns out your best people while preventing knowledge transfer to newer team members. Respect the rotation even when it feels slower. Treat deviation as the exception requiring clear justification.

Stage Three: 10-20 Engineers

Team size now enables sophisticated approaches but also creates coordination challenges. What worked with ten engineers requires adjustment at twenty.

Split Rotations

The defining transition at this stage: moving from one shared rotation to multiple service-specific or team-based rotations. A startup with backend, frontend, and infrastructure teams benefits from separate rotations where specialists handle their domains.

Benefits include reduced alert noise for individual engineers, faster resolution through domain expertise, and clearer ownership boundaries. Trade-offs include coordination overhead and potential gaps when incidents span multiple teams.

Implementation approach: Start with two rotations. Monitor handoff patterns between teams. Adjust boundaries based on actual incident distribution rather than organizational chart assumptions.

Implement Follow-the-Sun

If your startup has distributed teams across multiple regions, this stage enables follow-the-sun coverage where on-call responsibility moves with the workday around the globe.

Asia-Pacific engineers cover their business hours, hand off to Europe, who hand off to Americas. Everyone works normal hours. Nobody carries permanent night shift duty.

Requires minimum three to four engineers per region for sustainable rotation within each timezone, but completely eliminates the cognitive and health costs of regular overnight alerts. The coordination overhead of handoffs proves worthwhile compared to perpetual sleep disruption.

Automate Common Response Tasks

With sufficient incident history, patterns emerge. Database connections timing out follow predictable investigation steps. Service restarts resolve most transient failures. Memory pressure alerts benefit from standard capacity adjustments.

Research from 2025 identifies repetitive response tasks as the biggest cause of on-call fatigue among incident responders. Automation directly addresses this primary burnout driver.

Create executable runbooks with specific commands, not vague guidance. Implement automation that attempts standard remediation before paging humans. Track which automated fixes succeed versus require escalation, then continuously refine based on patterns.

Stage Four: 20 Plus Engineers

At this scale, on-call becomes an operational discipline requiring dedicated attention rather than something engineering managers handle part-time.

Specialized Rotations

Beyond team-based rotations, implement subject matter expert coverage for complex subsystems. Database specialists, network engineers, and security experts maintain separate schedules for their domains.

Primary on-call handles initial triage and investigation. When incidents require specialized knowledge, they escalate to domain expert rotations rather than struggling alone or waking the entire team.

Sophisticated Scheduling

Basic weekly rotations remain common, but larger teams benefit from fair distribution algorithms that maximize time between on-call periods for each engineer rather than simple sequential rotation.

Fair distribution spreads shifts evenly across scheduled days, optimizing for recovery time. Combined with roster-wide holiday exclusions and flexible override systems for personal circumstances, this maintains sustainable workload distribution even as alert volume increases.

Platforms supporting this complexity provide configurable rotation strategies, preview generation before publishing schedule changes, and override mechanisms that allow shift swaps without permanent rotation changes.

Measure and Optimize

At scale, intuition fails. Track quantitative metrics: alerts per on-call period, overnight interruption frequency, time to acknowledge, incident duration. Target fewer than five alerts per week, maximum two overnight interruptions, acknowledgment within five minutes.

Complement quantitative measurement with regular team feedback. Anonymous surveys reveal problems mathematical metrics miss. Engineers experiencing unsustainable burden surface issues before they drive attrition.

Common Scaling Mistakes

Premature complexity: Implementing enterprise-grade on-call infrastructure at five engineers wastes energy better spent on product development. Match sophistication to actual needs.

Delayed formalization: Waiting until ten engineers to establish basic rotations creates technical debt in operational practices. Informal approaches that worked initially become painful to formalize later.

Ignoring compensation: On-call duty restricts personal freedom and creates ongoing stress. Startups that neglect fair compensation—whether financial stipends, time off, or reduced workload during on-call weeks—see accelerated turnover among precisely the experienced engineers they most need to retain.

Skipping documentation: Rapid growth prevents real-time knowledge transfer. The engineering practices that work with five close-knit engineers fail completely when onboarding happens monthly. Documentation becomes infrastructure, not bureaucracy.

Cultural Foundations

Technical implementation matters, but culture determines whether on-call remains sustainable as startups scale.

Blameless response: Fear-based incident response compounds on-call stress. When engineers worry about blame for midnight decisions made under pressure, psychological safety erodes. Treat incidents as learning opportunities focused on system improvement rather than individual mistakes.

Founder visibility: Leadership participation in early rotations and continued engagement with on-call challenges signals organizational values. Founders who remain connected to operational reality make better decisions about infrastructure investment and team capacity.

Continuous improvement: Empower engineers experiencing on-call pain to fix what hurts. Allocate dedicated capacity for operational improvements: fixing problematic alerts, developing automation, improving documentation, enhancing tooling. Operational excellence deserves engineering time and resources.

Getting the Timing Right

The hardest question: when to transition between stages? Watch for specific signals rather than arbitrary headcount targets.

Formalize rotations when: Alert responsibility causes conflict, vacation planning creates coverage gaps, or founders become operational bottlenecks.

Split rotations when: Single-team rotations generate excessive alerts for individuals, specialized knowledge creates informal escalation patterns, or coordination overhead outweighs rotation complexity.

Implement follow-the-sun when: Regular overnight alerts impact engineer health, retention concerns emerge around night shift burden, or distributed team presence makes regional coverage feasible.

Treat these transitions as engineering problems requiring thoughtful design rather than copying whatever enterprise playbook seems authoritative.

Final Thoughts

Scaling on-call at startups requires balancing operational reliability against team capacity constraints that larger companies never face. Every formalization step adds overhead. Every delay creates technical debt in operational practices.

Start simple with clear expectations and basic rotation. Add sophistication as team size justifies complexity. Measure both quantitative burden metrics and qualitative team feedback. Maintain cultural foundations that make on-call sustainable regardless of technical implementation sophistication.

The organizations that navigate this evolution successfully treat on-call as core infrastructure deserving intentional design, fair compensation, and continuous improvement—not an unfortunate operational necessity to minimize and ignore.

Tools support the journey but don’t substitute for good judgment about timing and appropriate complexity for current team size. The goal remains consistent across all stages: operational reliability maintained by engineers who feel supported, compensated fairly, and able to sustain this work long-term.