Free tools

Free uptime tools

Calculators and checks for everyday uptime work. Free, no signup required.

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SLA & Uptime Calculator

Turn 99.9% into real minutes of downtime per day, month and year, or convert an outage into the uptime it cost you.
Cron Expression Generator

Build a crontab schedule in clicks, decode any cron expression into plain English, and preview the next run times.
DNS Lookup

See every record for a domain from one resolver: A, AAAA, MX, TXT, CNAME, NS, SOA and CAA, plus reverse DNS for an IP.
DNS Checker

Compare one record across Google, Cloudflare, DNS.SB and AliDNS at once to confirm a DNS change has propagated everywhere.
SPF Checker

Validate your SPF record and count its DNS lookups against the limit of 10 that quietly breaks email delivery.
DMARC Checker

Look up your DMARC record, read your enforcement policy, and see where your aggregate reports are sent.
DKIM Checker

Look up a DKIM record by selector and confirm the signing key is published and has not been revoked.
Is Website Down?

Check from the outside whether a website is down for everyone or just for you, and see live status for popular services.
Bulk URL Checker

Paste up to 25 URLs and see the HTTP status code, full redirect chain and response headers for each one at once.
Domain Expiry Checker

See when any domain expires and how many days are left, with its registrar, nameservers and transfer lock status.
Website IP Lookup

Find the IPv4 and IPv6 addresses behind a domain, with reverse DNS, the CDN in front of it and where each one is registered.
Email Validator

Check an address for valid syntax and working MX records, and spot disposable domains and role accounts before you send.
HAR File Analyzer

Open a .har capture to see the request waterfall, page load timings and third-party weight. The file never leaves your browser.

DNS record lookups

Query one record type at a time for any domain.

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