Uptime calculator
How much downtime 99.9%, 99.95% or any other availability target allows a day, a week, a month and a year, and what a server's uptime reading means in days.
Free tools
Free uptime and reliability tools
Small tools for the questions an on-call engineer actually types into a search box: how much downtime a 99.9% target allows, when a certificate expires, what a cron expression means, how many hours a rotation costs each person, whether a site is down for everyone or just for you. Each one answers in the browser or with one request to our servers, needs no account, stores nothing you type, and can be called from a script or an AI agent through the no-key free tools API.
They are built by Uptimely, the uptime monitoring and status page service, and each one links to the monitor that does the same job continuously. A check tells you about now; a monitor tells you the moment it changes.
Calculators and checkers
SSL certificate checker
Enter a hostname to read the certificate it serves: expiry date and days left, issuer, the names it covers and whether the chain is trusted.
Cron expression explainer
Paste a five-field crontab expression to read what it means in plain English and when it runs next, in UTC.
On-call schedule calculator
For a rotation of a given size and coverage, the on-call hours a week, weeks a year and shifts a year each person carries.
Postmortem template generator
Answer a few questions and copy a blameless incident postmortem in Markdown; nothing you type is stored.
Status badge builder
Copy the HTML or Markdown for a live status badge of a public Uptimely status page, for a README, docs or website.
Live checks
Is it down?
A live check of any public website: whether it answers, its HTTP status, response time and HTTPS certificate, with one page per popular site.
Service status
The current status, components and recent incidents of popular services, read from each vendor's official status page.
What these tools do not do
Each check runs once, from one location, when you ask for it. None of them watches anything afterwards, so a certificate that is fine today can still lapse unnoticed next month, and a site that is up for the checker can still be down in your region.
When one check is not enough
An Uptimely monitor runs the same check every minute from the same vantage, keeps the history, and alerts you by email, SMS, phone call, Slack, Discord or browser push when the answer changes. The Free plan includes 10 monitors and a public status page, with no credit card. See the feature pages for what each monitor type checks.
Uptimely's Free plan has 10 monitors, 1 status page and 1-minute checks, with no credit card. Pro comes with a 14-day free trial.
Start free →Glossary of uptime terms · HTTP and network error guides · Uptimely vs the alternatives
Verified by the Uptimely team.