Free tools & live data for people who run things on the internet
SysOSX is a small set of sharp, free tools for site owners, indie developers and small teams. Check a website's health in seconds, watch the dates that quietly take sites offline — certificate expiry, domain expiry — and work out what LLM APIs really cost before the invoice arrives. No sign-up, no clutter: one tool, one answer, one clear next step.
The tools
Website Health Check
One domain in, a full report out: is it online, how fast does it answer, when does the TLS certificate expire, when does the domain itself expire, and what do the DNS records say? The flagship check, and the fastest way to spot an avoidable outage.
Check a domain → 🔒SSL Checker
Inspect any site's TLS certificate: issuer, validity window, days remaining, chain and hostname match, and the protocol in use. An expired certificate is a browser warning and a lost customer — see the countdown before your visitors do.
Check a certificate → 📅Domain Expiry Checker
Find a domain's registrar, registration date and — most importantly — its expiry date and days remaining, straight from registry data, plus the DNS records that point at it. Lapsed domains get re-registered by strangers fast; know your date.
Check an expiry date → 🧮LLM API Cost Calculator
Pick up to four models — or compare them all — enter your monthly requests and average tokens per request, and see the monthly bill per model, cheapest first. Peak/off-peak traps and scheduled price rises are surfaced, not buried.
Estimate a bill → 🏆LLM Pricing Leaderboard
Every model we track, in one sortable table: input, output and cached-input prices, context window, a link to the official source and the date each price was last verified. Prices we could not confirm on an official page are badged, never hidden.
See the leaderboard →A check tells you about today. Monitoring tells you in time.
Certificates and domains expire on a schedule you do not control, and sites go down at the worst possible moment. The tools above are one-off snapshots; myeventwatch watches the same signals continuously and alerts you by email, Telegram, webhook and more — weeks before an expiry, minutes after an outage. Every report on SysOSX links straight to a free monitoring setup for the domain you just checked.
From the blog
The SysOSX blog archive — years of hands-on notes on Linux, servers, self-hosting and running systems — is still here and still growing its archive. The tools are the new front door; the writing lives on, unchanged, at its original home.
Why these tools?
Most outages that hurt small sites are not exotic. They are a certificate nobody renewed, a domain that lapsed over a holiday, a DNS record edited once and never re-checked, or an API bill that doubled because a pricing page changed quietly. Each of those is cheap to detect and expensive to discover late. SysOSX exists to make the detection free and instant — and, where a one-off check is not enough, to hand you over to continuous monitoring that does the watching for you.
The LLM pages follow the same philosophy. Model prices change often, promotional rates expire, and headline numbers hide peak-hour multipliers and scheduled increases. Our calculator and leaderboard show the source and the verification date for every price, flag the ones we have not been able to confirm on an official page, and spell out the footnotes that change the bill. Live data, honestly labelled, beats a confident guess.