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Calculators and downloads for designing and operating critical systems. Using them takes no signup; the premium downloads (PDF and Markdown) come with your email.
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Availability calculator
Turn your SLA target into real downtime —per year, month and week— and check your architecture against the 8-domain checklist. The printable version is free; the PDF and Markdown, with your email.
- SLA → allowed downtime (year / month / week)
- How much of your unavailability budget is left
- 8-domain checklist: PDF, Markdown, or printable
On the way
Retry budget
Backoff, jitter and the worst case of a retry storm against a failing dependency.
SLO burn-rate
How much error budget is left, how fast it burns, and when to alert.
Latency and percentiles
p50 / p95 / p99 and how the tail dominates with several calls in parallel.
Capacity and saturation
Utilization, queues and headroom for the worst case: losing a zone during a peak.
Cost of downtime
Turn each nine into money and justify how far it's worth investing in availability.
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