SysAdminToolsSysAdminTools
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SysAdminTools

Free Network & IT Tools

Subnet calculator, DNS lookup, SSL checker, password generator, email authentication tools, and more. Built for sysadmins and network engineers.

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Network

🌐

Show My IP

Display your public IP address, ISP, and ASN

📍

IP Geolocation

Find the geographic location of any IP address

🔢

Subnet Calculator

Calculate network addresses, ranges, and subnets from CIDR notation

📊

Bandwidth Calculator

Convert and calculate bandwidth, transfer times, and data sizes

📐

MTU Calculator

Calculate optimal MTU size accounting for encapsulation overhead

🏭

MAC Address Lookup

Find the vendor/manufacturer from a MAC address

⚡

Speed Test

Test your internet download and upload speed

✅

Server Status Checker

Check if a website or server is up and reachable

🔍

Port Scanner

Scan any server or IP for open TCP ports

🚪

Port Reference

Common network ports and their services

DNS

🔍

DNS Lookup

Query DNS records for any domain — A, AAAA, MX, CNAME, TXT, NS

📋

Whois Lookup

Look up domain registration and ownership information

Email

🛡️

SPF Builder & Checker

Build and validate SPF records for your domain

🔑

DKIM Checker

Verify DKIM records and key configuration

📧

DMARC Builder & Checker

Build and validate DMARC policies for email authentication

📬

Email Deliverability Tester

Score your email setup for deliverability issues

📨

Email Header Analyzer

Trace email delivery path, detect delays, and check authentication results

🚫

Blacklist Checker

Check if an IP or domain is listed on major email blacklists (DNSBL)

Security

🔒

SSL Certificate Checker

Check SSL/TLS certificate details and expiry dates

🔐

Password Generator

Generate secure passwords and passphrases with full customization

💀

One-Time Secret

Share passwords and secrets via self-destructing links

Web

📡

HTTP Header Checker

Inspect HTTP response headers for any URL

Utility

🔄

Base64 / Hex / Binary Converter

Encode and decode between Base64, hex, binary, and text

⏰

Cron Expression Generator

Build and explain cron schedule expressions visually

🎯

Regex Tester

Test and debug regular expressions with live matching

🎟️

JWT Decoder

Decode and inspect JSON Web Tokens

Resources

🖥️

Remote Access Tools

Curated directory of free remote desktop and access tools

📦

Essential IT Software

Curated list of must-have free software for sysadmins and IT professionals

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Frequently Asked Questions

What tools are available on SysAdminTools.cc?
We offer 25+ free tools including subnet calculator, DNS lookup, WHOIS lookup, SSL checker, speed test, email deliverability tester, SPF/DKIM/DMARC builders, password generator, blacklist checker, and more. All tools work in your browser with no signup required.
Are these tools free to use?
Yes, all tools on SysAdminTools.cc are completely free with no registration or login required. They run directly in your browser or use our lightweight API endpoints.
How do I check my email deliverability?
Use our Email Deliverability Tester to send a test email and receive a score out of 10. It checks SPF, DKIM, DMARC, reverse DNS, blacklists, SpamAssassin score, and 15+ other factors that affect email delivery.
How do I calculate subnets from CIDR notation?
Enter a CIDR notation (like 192.168.1.0/24) in our Subnet Calculator to instantly see the network address, broadcast address, host range, number of usable hosts, wildcard mask, and binary representation.
How do I check if my IP is blacklisted?
Use our Blacklist Checker to test your IP address or domain against major email blacklists (DNSBL/RBL) including Spamhaus, Barracuda, SORBS, and others. Results are instant and free.