Free tools
Free tools for reliability teams.
Quick, no-signup calculators and utilities for uptime, SLAs, and scheduled jobs. Built by the team behind Spectra — the all-in-one monitoring platform.
Uptime / SLA calculator
Turn an uptime percentage into the downtime it actually allows — per day, month, and year.
Downtime cost calculator
Estimate what an hour of downtime really costs your business in lost revenue.
Error budget calculator
Convert an SLO into a concrete error budget, and see how much you've spent.
Cron expression generator
Build a cron schedule with dropdowns (standard or Quartz), explain it, and preview its next run times.
DNS lookup
Check any domain's A, AAAA, MX, TXT, NS, CNAME, CAA, and SOA records instantly.
Stop calculating downtime — start preventing it
Spectra watches your websites, APIs, servers, SSL certificates, ports, and cron jobs from multiple regions and alerts you the moment something breaks. Free forever, no credit card.
