16 free tools available

Free Web Diagnostic Tools

Analyze, diagnose, and monitor any website. No signup, no artificial limits.

Whether you’re a developer debugging a production issue, an SEO specialist auditing a site, or a sysadmin checking server health, FlashMon’s free tools give you instant answers. Check if a site is down, inspect SSL certificates, trace DNS propagation, scan open ports, analyze security headers, and much more — all from your browser, with no account required. Each tool runs real checks against your target and returns results in seconds.

Availability & Performance

Website Down Checker

Check if a website is accessible globally or just for you

Global Ping Tool

Measure network latency from multiple global locations

Speed Test

Analyze your website performance with Core Web Vitals metrics

HTTP/2 & HTTP/3 Test

Check if your website supports modern transfer protocols

DNS & Domain

DNS Lookup

Query all DNS records for any domain

DNS Propagation Checker

Check if your DNS changes have propagated globally

WHOIS Lookup

Discover who registered a domain, when it expires and more

Domain Age Checker

Find out how long a domain has been registered

Security

SSL Checker

Verify SSL certificates, validity and security health

Security Headers

Analyze your site HTTP security headers and receive a grade

Blacklist Checker

Check if your domain or IP is on any blocklist

HTTP & Network

HTTP Status Checker

Analyze response headers and trace redirect chains

Redirect Checker

Trace the full redirect chain of a URL

Traceroute Online

Trace the packet route to any server

Port Scanner

Check which ports are open on a server

Email

MX Lookup

Check mail servers, SPF, DMARC and DKIM for your domain

Need continuous monitoring?

Try FlashMon Pro

Run these same checks automatically every 60 seconds. Get instant alerts via Slack, email, or Discord when something breaks. Track uptime history and SLA percentages over months.

Try FlashMon Pro