Frequently asked questions

Everything about how a check works: what we measure, when we call a site down, and how your checks are handled. Can’t find it here? Send us a message.

How do I check if a website is down?

Type the address into the box on the home page and press Check. We request the site from our own server and tell you whether it is up, slow, reachable but returning an error, or offline. A healthy site is usually confirmed in well under a second.

Why do you try three times before calling a site down?

A single failed request does not prove that a site is offline. Your IP might be blocked, there could be a temporary network problem, or the site might only be reachable from certain regions. We therefore make three attempts with a short pause between them, and only report DOWN when every attempt fails. Any attempt that returns an HTTP status below 500 rules out a DOWN verdict.

What does "Reachable, but error" mean?

The server is online and answering, but the page itself is not OK. We report this for HTTP 4xx responses such as 403 Forbidden or 404 Not Found, and for redirect loops. The site is not down — something in the server or its configuration is wrong.

What counts as slow?

When a site returns a success status but takes longer than 3 seconds, we label it SLOW. The site works, so we never call it down for being slow.

A site shows as up here, but it will not load for me. How?

We check from our own server, so the result says something about the public internet — not about your device. If a site works for us but not for you, the problem is usually local: your DNS resolver, your Wi-Fi, a browser extension, a VPN, or a block on your own network. It can also be the other way around: a site may be geo-blocked and answer us while refusing your region.

Can I use downcheck.io for continuous monitoring or alerts?

No. This is an on-demand checker, not a monitoring service: there are no accounts, no schedules and no alerts, and the rate limits are deliberately low. For continuous monitoring you want a tool that runs from several locations and keeps long-term history. If you just need to know whether our own service is healthy, GET /api/health returns a small JSON status.

Can I check localhost or my own internal network?

No. For security reasons we refuse internal hosts and private IP addresses such as localhost, 127.0.0.1, 10.x.x.x, 192.168.x.x and 169.254.169.254, as well as public hostnames that resolve to them. That stops our checker from being used to probe private networks.

Is downcheck.io free, and do you store my checks?

It is free and there is no account. We do not store the addresses you check. The "Recently checked" list on the home page shows only the domain name — never the path or the query string. So that a single visitor cannot fill that list, each entry carries a salted one-way hash of the visitor, which limits the same visitor to two entries; the IP address itself is never kept. Everything is held in memory and wiped when the server restarts.

What is the "Recently checked" list?

A shared list of the last ten checks, visible to every visitor — not a personal history. It shows domain names only, at most two entries per visitor, and it is cleared every time the server restarts. That means it can be empty right after a deployment.

Why are example.com and www.example.com treated as the same site?

In the "Recently checked" list we strip a leading "www." so that both spellings of the same site do not fill two rows. The check itself uses exactly the address you typed, including any subdomain.

Is checking a website this way intrusive?

We send one ordinary GET request per attempt with browser-like headers, and we identify ourselves in the user agent. We read the response headers only and discard the body immediately, so we never download your pages. Content behind a login is never touched.

Can you tell me why a site is down?

We can tell you exactly what we observed: a timeout, a DNS failure, a refused connection, a TLS error or a 5xx response. If a site is unreachable from our server but works fine for you, that usually points to a firewall or a geo-block on the site's side.

Why was my check refused?

Two possible reasons. The address was rejected before we made any request — an unsupported scheme, credentials in the URL, or an internal or private address. Or you hit a rate limit: ten checks per minute per visitor, two at the same time. In both cases the message on screen tells you which of the two it was.