Free IT Tools for Sysadmins
33 practical tools for the things administrators do every week: check DNS, trace a failing email, verify a certificate, decode a token or convert a config file. Each tool is listed under the task it solves, with a plain sentence on when to reach for it. No sign-up, and most run in your browser.
Network & DNS
Find out where an address lives, what its DNS says, who owns a domain, and whether a host answers.
IP Address Lookup
Shows the ISP, city, country and network of an IP address, or of yours.
DNS Records Lookup
Queries A, AAAA, MX, TXT, NS, CNAME and other records through Cloudflare DNS over HTTPS.
WHOIS Lookup
Registrar, creation and expiry dates, status and name servers via RDAP.
Ping & Port Scanner
Checks whether a host answers and whether chosen TCP ports are open. Only scan systems you own or have permission to test.
IPv4 Subnet Calculator
Network address, broadcast, usable range and mask for any CIDR.
Email & Exchange
Trace, test and fix mail delivery without guessing.
Security & Trust
Check certificates, headers, links and credentials before they cause an incident.
SSL Certificate Checker
Issuer, validity dates and days remaining for a domain's certificate.
HTTP Headers Checker
Shows response headers, redirect chains and which security headers are present.
URL Scanner / Phishing Detector
Checks a link against VirusTotal for malware and phishing.
Hash Generator & Lookup
MD5, SHA-1, SHA-256 and SHA-512 hashes, plus a known-file lookup.
Password Strength & Generator
Scores a password and checks it against known breaches without sending the password itself.
JWT Decoder
Decodes a token's header and payload and shows the expiry, in your browser.
Random Password Generator
Cryptographically secure passwords generated locally.
UUID Generator
Random v4 UUIDs in bulk.
Data & Developer
Convert, format and test the text formats admins meet every day.
JSON Formatter & Validator
Pretty-print, minify and validate JSON.
YAML to JSON Converter
Converts between YAML and JSON.
XML to JSON Converter
Converts between XML and JSON, keeping attributes.
CSV to JSON Converter
Converts CSV and JSON, handling quotes and delimiters.
Regex Tester
Tests patterns with live match highlighting.
Base64 Encoder & Decoder
Encodes and decodes with correct UTF-8 handling.
URL Encoder & Decoder
Percent-encodes and decodes URLs and components.
Unix Timestamp Converter
Converts epoch times and readable dates.
Text Diff Checker
Compares two texts line by line.
Number Base Converter
Binary, octal, decimal, hex and any base to 36.
Hash Generator (SHA-2)
SHA-1 and SHA-2 hashes of text in your browser.
Markdown Previewer
Live side by side Markdown preview.
HTML Entity Encoder
Encodes and decodes HTML entities.
Meta Tag Generator
SEO, Open Graph and Twitter Card tags.
Windows & Deployment
Tools for the messy parts of Windows administration.
How to use these tools
- Pick the category that matches your problem, such as Email & Exchange for a delivery issue.
- Open the tool and enter the domain, address, header or text.
- Read the result, then use the "when to use" note to choose the next tool.
FAQ
Are these IT tools free?
Yes. All of them are free with no sign-up. Most run entirely in your browser.
Do the tools send my data anywhere?
Client-side tools such as the JSON formatter, JWT decoder and converters process text in your browser. Network tools such as DNS, WHOIS, SSL and port checks must contact outside services to answer, and the privacy policy explains what is sent.
Can I scan any server with the port scanner?
Only scan systems you own or have written permission to test. The scanner is rate limited and refuses private and internal addresses.
Which tool should I use first when email fails?
Start with the Email Header Analyzer on a failing message, then check SPF, DKIM and DMARC, and finally Autodiscover if the problem is Outlook connecting.