About Sysadmin Tools

A small collection of free, no-login utilities for IT professionals. Built because the existing options are either bloated with ads, slow, or stuck in 2008.

What this site is

Sysadmin Tools is a launchpad for the things you look up at 9am Monday and again at 2am Friday when something is on fire. Each tool answers one question, fast, with no signup and no nag. DNS lookups, subnet math, what's-IP-with-my-traffic, WHOIS, TLS chain checks, header inspection, email authentication lookups, DNS propagation across providers — the kind of workhorses that pay for themselves in the first outage they help you debug.

Where other sites have wrapped the same utilities in three rounds of "please create an account" and a video ad, we've kept this one as a single page per tool with a single input box and a single result.

Why we built it

The operator is a network and systems engineer who got tired of pulling up a dozen different sites, each with a different login and a different nag UI, to do the same five lookups every week. The tools here are the ones the operator actually uses. We've skipped the ones we don't (a port scanner you'd actually be afraid to run from a shared cloud IP, for example).

We'd rather have ten tools that work than fifty that are half-finished.

What we don't do

• We don't require an account. There is no sign-up, no login, no email collection at any point.
• We don't run third-party tracking scripts.No Facebook pixel, no Google Analytics. If we ever want aggregate traffic data, we use privacy-respecting providers (Plausible or Cloudflare Web Analytics) that don't set cookies and don't profile you across sites.
• We don't log your queries. DNS queries are run server-side, returned to you, and dropped. WHOIS queries are similar. Your IP address is detected from request headers and never stored.
• We don't run on Shopify.No, really, this isn't a dropshipped side hustle. It's a Next.js app behind a Caddy reverse proxy on a small VPS, and the code is in a private Git repository.
• We don't sell your data. There is no data to sell. See Privacy.

What we do

Ads, occasionally, served by Google AdSense. They appear as a slot below the tool output on long-form pages (like this one). They are clearly labeled as ads and do not gate the tool itself. If you have ad personalization turned off, we still get paid less but you still get the tools. We consider that an acceptable trade.

The HTTP stack is behind a Cloudflare proxy for DoS protection and edge caching. The container is stateless; we can rebuild it from the repository at any time.

How it's built

Next.js 16 (App Router), React 19, TypeScript, Tailwind CSS v4, with the standard sysadmin tool bag underneath: dig via child_processfor DNS, OpenSSL for the TLS chain check, Node's built-in http module for header inspection. Subnet math and IP parsing run entirely in your browser — the server never sees that input.

Deployed as a Docker container behind Caddy (which terminates TLS and forwards to the container on loopback). Caddy and the app are managed by docker compose. Source code is in a private Git repository; deploys are docker compose up -d --build app.

What's coming

Three things on the near roadmap, in rough priority order:

1. A real-time BGP / Internet Health panel. We'll start with the Cloudflare and ThousandEyes public status feeds and grow from there.
2. An expandable WHOIS history timeline, sourced from Zonefiles / RDAP archives rather than live lookups.
3. A CIDR aggregation tool — paste a bunch of /24s, get the minimum covering prefix(es). Useful during mergers.

Long-term ideas include a small, opinionated DNS zone-file validator (catches the classic mistakes) and an MTA-STS policy tester. We'll publish whichever of these actually lands, in the blog.

Who runs it

The site is operated by an individual, not a company. If a tool breaks, it's because the operator pushed a bad config or a third-party provider changed their endpoint, and the operator is fixing it. This is also who you're emailing if you write to [email protected].

Operator: a senior network and systems admin working in NYC. Background in identity, endpoint, cloud, and automation. Day job running Microsoft AD, Intune, M365, and a fair amount of Palo Alto and Meraki. Off-hours builds this and other small things.

Contact

• General: [email protected]
• Bug reports / feature requests: GitHub issues (open an issue, no account required to view).
• Abuse: [email protected] (see Terms for what counts).
• Press / partnership: [email protected] — slow response window, no automated pitch bots please.

Status and incident reporting

Each tool surfaces its own error state inline; if you see a stack trace, the bug is on our side and it has been logged. For site-wide outages we publish a note on the homepage banner and the GitHub repo when one is open. There is no third-party status page; this site is the surface we operate.

Credits and attributions

The site makes use of the following third-party data sources, without whom it would not work:

• ip-api.com — free tier IP geolocation.
• CISA Known Exploited Vulnerabilities catalog and the NVD feed, both public domain.
• IANA Service Name and Transport Protocol Port Number Registry, public domain.
• Public DNS resolvers operated by Cloudflare, Google, Quad9, and OpenDNS — thank you for the free recursion.

The site's logo and design are original work. The font is Geist, by Vercel, under the SIL Open Font License.