What SiteDownCheck is
SiteDownCheck is a free website diagnostics and uptime monitoring service. You type in a domain, URL or IP address, and the site runs a real check from its own servers and shows you what it found: whether the site responds, how long it takes, what the certificate looks like, how DNS is configured, and where a problem most likely sits.
The service is operated by Your Name or Company Name in India. It is aimed at people who run websites: site owners, developers, freelancers, small agencies, and the people in a company who get the message "the site is down, can you check?" and need an answer that is more specific than "it works for me".
Why it exists
When a website stops working, the first minutes matter. The usual sequence is to refresh the page, ask a colleague, and then guess. The problem could be the web server, an expired certificate, a DNS record that changed, a CDN error, a blocklist entry, or something that only affects one network. Each of these has a different fix, and telling them apart normally means running several command-line tools in the right order.
SiteDownCheck packages those checks into plain-language tools and explains the result. Alongside the tools, the guides section explains the underlying concepts, such as what a 502 error means, how SPF lookups are counted, or why a certificate can be valid in one browser and rejected in another.
What you can do here
There are around 70 free tools, grouped by the kind of question they answer.
| Group | What it covers |
|---|---|
| Availability | HTTP status, redirect checker and debugger, port checker, outage root-cause finder, multi-location check, maintenance versus outage, Cloudflare error checker |
| Health and speed | Health check, speed test, Core Web Vitals through the Google PageSpeed API, broken links, robots.txt and sitemap, meta tags, page weight, HTTP/2 and HTTP/3, third-party scripts, full site report |
| Security | SSL certificate, certificate chain, TLS versions, security headers, HSTS, blacklist (DNSBL), mixed content, cookies, CORS, security.txt, bulk SSL, dangling DNS |
| DNS and domain | DNS records, MX, NS, SPF, DKIM and DMARC, SPF and DMARC generators, WHOIS through RDAP, domain age, DNSSEC, email deliverability, subdomain finder, DNS history, domain expiry watch |
| Hosting and network | What is my IP, IP lookup, reverse IP, ASN lookup, hosting provider, CDN detector, HTTP header viewer |
| Developer tools | JSON, Base64, URL, JWT, timestamp, regex and QR tools that run entirely in your browser |
| Monitoring | Uptime monitor, cron and heartbeat monitor, uptime badges, status pages, status widget, post-mortem generator, API |
The developer tools do their work locally in your browser, so what you paste into them is not sent to our servers.
Uptime monitoring
Checking a site once is useful. Being told when it breaks is better. The free monitoring plan includes:
- 3 monitors, with checks as often as every 5 minutes.
- Failure confirmation: a failure must be seen twice before an alert is sent, which cuts down false alarms from a single dropped connection.
- Alerts by email and by webhook (Slack, Discord or a generic webhook).
- Keyword checks, slow-response alerts and JSON or API response checks.
- Maintenance windows, so planned work does not trigger alerts.
- SSL expiry, domain expiry, DNS change and certificate change alerts.
- Heartbeat monitors for cron jobs and background tasks, using a ping URL with an optional /fail endpoint.
- Public status pages (with a white-label option), uptime badges, a response-time chart, a monthly emailed report, and a calendar (.ics) export of expiry dates.
- An API key with 200 requests per day on the free plan.
A Pro plan is planned and marked as coming soon. The intended scope is 50 monitors, 1-minute checks, SMS alerts, custom status page domains and multi-region checks. Nothing about it is available to buy today, and the free plan is not being reduced to make room for it. If you lost access to a monitor, see recover a monitor.
Guides
The guides section has about 32 long-form articles in seven categories: Downtime and errors, Monitoring, DNS and domains, Email, SSL and security, Performance, and Web basics. Each guide shows an updated date, includes a short FAQ, and links to the tools that help you act on what you have just read. They are written by the SiteDownCheck Editorial team; the standards they follow are set out in the editorial policy.
How results are produced
Every check runs from SiteDownCheck's own servers. Unless extra probe servers are configured, that means a single location, so a result describes what that location saw at that moment. It can differ from what you see on your own network, and the tools say so where it matters.
A few rules apply across the site:
- Private and internal addresses are refused, so the service cannot be used to probe networks it should not reach.
- HTTP-based tools only connect to ports 80, 443, 8080 and 8443. The port checker has its own allow-list.
- Rate limits apply to keep the service usable for everyone.
- A site is reported as up unless the connection fails or the status is 5xx, 404 or 410. Responses such as 401, 403 and 429 are shown as "up (access restricted)", because the server answered but declined to serve us.
The full explanation, tool family by tool family, is on the methodology page.
Principles we hold ourselves to
We say when a check could not finish. A timeout, a refused connection, a blocked probe and a failed third-party lookup are different outcomes, and the result tells you which one happened instead of showing a vague error or a guess.
We do not claim perfect accuracy. Network measurements depend on where and when they are made. We describe what was measured and where the method has limits.
Results are not for sale. There is no paid placement in tool results, and nobody can pay to change what a tool reports about a site.
Advertising is separate. If ads are enabled, they are labelled, they appear outside the results, and they are never mixed into tool output. Where consent is required, ads are shown only after consent.
Corrections are welcome. If a tool or guide gets something wrong, email contact@sitedowncheck.com. We fix it and note the update date on the page.
Privacy in brief
SiteDownCheck does not use tracking cookies. Your recent tool inputs are kept only in your browser's localStorage, on your device, so you can reuse them. If you create a monitor, we store the email address of the owner so we can send alerts. IP addresses are used for rate limiting and abuse prevention. Optional Google AdSense ads may be enabled later, with consent where the law requires it. The Privacy Policy has the full details.
How the site is funded
The tools are free to use. Running them costs money for servers, bandwidth and data services, and the intention is to cover those costs through optional advertising and, later, the paid Pro monitoring plan. We think it matters to be plain about this. A guide may mention our own monitoring product where it is relevant, and the editorial policy explains how we handle that conflict of interest.
What the service is not
SiteDownCheck is a diagnostic aid. It is not a penetration test, a compliance audit or a legal opinion. A clean security-header result does not mean a site is secure, and a passing blacklist check does not guarantee that email will reach the inbox. Use the output as evidence to guide your next step, and confirm important findings with your own tools or your hosting provider.
Get in touch
Questions, bug reports, tool requests and corrections are all welcome. Use the contact page or write to contact@sitedowncheck.com. Please include the exact URL you checked and, if you can, the time, because that lets us reproduce what you saw.