free tools for developers and SREs.
Small, fast calculators and generators, no sign-up. We built them for our own work watching uptime and kept them free for yours.
Uptime SLA & Downtime Calculator
Turn an uptime percentage into allowed downtime per day, week, month and year. A free SLA and SLO calculator with the full nines reference table.
Cron Expression Generator & Parser
Build and read cron expressions in plain English, with the next run times and a reference table of the most common schedules. Free, no sign-up.
Error Budget & Burn Rate Calculator
Turn an SLO target and your measured availability into error budget spent, budget left and burn rate, with a burn-rate reference table. Free, no sign-up.
Watch the things these tools measure.
Uptimepage checks your endpoints every minute, opens an incident the moment one fails, and shows the record on a public status page. Start free, no card.