40+ Free Network Tools

Network diagnostics, simplified.

DNS, email, ports, SSL, WHOIS and 30+ more tools — all in one place. Free web interface and powerful REST API.

DNS & Domain

6 tools

Email & Deliverability

8 tools

Network & IP

9 tools

Web & Security

6 tools

Images & Media

11 tools

Text Tools

7 tools

Utilities

6 tools

Popular Tools

Most used tools by our community

All Tools

DNS Lookup

Check DNS records online for any domain — A, AAAA, MX, NS, TXT, CNAME, SOA. Free DNS lookup tool with instant nslookup results, TTL values, and authoritative server data.

WHOIS Lookup

Find domain owner and registration details — registrar, creation date, expiry, nameservers, and registrant info. Free WHOIS domain lookup via WHOIS protocol.

Domain Age

Check when a domain was first registered and calculate its exact age. Useful for SEO analysis, trust evaluation, and domain research.

NS Checker

Verify nameserver configuration and delegation for any domain. Check NS records, response times, and consistency across DNS servers.

MX Lookup

Check MX records for any domain online. Discover mail servers handling email, view priorities, IP addresses, and mail routing configuration.

Blacklist Check

Check IP or domain against 100+ DNS blacklists (RBL/DNSBL). Free email blacklist checker to detect if your mail server is blocked and causing delivery issues.

Email Validator

Verify email address deliverability with syntax check, MX record validation, and SMTP verification. Detect disposable and invalid emails.

Header Analyzer

Parse raw email headers to trace message routing, check authentication results (SPF, DKIM, DMARC), and detect delivery delays.

Email Health

Comprehensive email health score for any domain — checks MX, SPF, DKIM, DMARC, and blacklists. Get an A-F grade with recommendations.

Port Scanner

Check open ports on any IP address online. Free port scanner to scan TCP/UDP ports, detect open, closed, and filtered states across common service ports or custom ranges.

Ping Test

Ping any website or IP address online. Free ping tool to measure round-trip time, packet loss, and network latency. Test connectivity from multiple servers.

IP Geolocation

Find IP address location on the map — country, city, region, ISP, ASN, timezone, and GPS coordinates. Free IP geolocation lookup for any IPv4 or IPv6 address.

What Is My IP

Instantly see your public IP address with geolocation details — country, city, ISP, and ASN. No tracking, no logs.

Internet Speed Test

Test your internet connection speed — download, upload, and ping. Measure real bandwidth performance instantly.

SSL Checker

Check SSL certificate for any domain online — certificate chain, expiration date, issuer, protocol versions. Verify if SSL is valid and properly configured.

HTTP Headers

Inspect HTTP response headers for any URL. Analyze security headers (HSTS, CSP, X-Frame-Options), caching policies, and server information.

Speed Test

Measure website loading speed — TTFB, total load time, page size, compression, and resource count. Get a performance rating for any URL.

Tech Detector

Detect technologies used by any website — CMS, frameworks, JavaScript libraries, CDN, hosting, analytics, and 40+ other technologies.

Image Converter & Compressor

Convert and compress images online — PNG to JPG, WebP to JPG, HEIC to JPG, AVIF, TIFF. Quality control, resize, batch processing up to 10 files. No upload to third-party servers.

Image Resizer

Resize images online to exact dimensions with aspect ratio control. Free image resizer — choose fit mode: cover, contain, fill, inside, or outside.

Web Optimizer

Auto-optimize images for the web — resize to max 2000px, convert to WebP format, and compress with optimal quality settings.

Text Analyzer

Count characters, words, sentences, paragraphs and lines. Character breakdown by type, reading time estimate, and average word length.

Case Converter

Convert text between 12 case formats — UPPER, lower, Title, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and more.

JSON Formatter & Validator

Format, validate, and beautify JSON online. Free JSON formatter with minification, structure depth analysis, key counting, and detailed error messages for invalid JSON.

UUID / ULID Generator

Generate UUID v1, v4, v7, ULID, and Nano ID. Analyze existing IDs — extract timestamps, detect versions. Custom prefixes, formats, batch generation.

All Tools

Browse all 53+ tools organized by category

DNS & Domain

6

DNS Lookup

Check DNS records online for any domain — A, AAAA, MX, NS, TXT, CNAME, SOA. Free DNS lookup tool with instant nslookup results, TTL values, and authoritative server data.

DNS Propagation

Check DNS propagation across 50+ global servers worldwide. Verify that DNS changes have fully propagated after updating records.

Reverse DNS

Resolve any IP address to its hostname using PTR record lookup. Verify reverse DNS configuration for email servers and network diagnostics.

WHOIS Lookup

Find domain owner and registration details — registrar, creation date, expiry, nameservers, and registrant info. Free WHOIS domain lookup via WHOIS protocol.

Domain Age

Check when a domain was first registered and calculate its exact age. Useful for SEO analysis, trust evaluation, and domain research.

NS Checker

Verify nameserver configuration and delegation for any domain. Check NS records, response times, and consistency across DNS servers.

Email & Deliverability

8

MX Lookup

Check MX records for any domain online. Discover mail servers handling email, view priorities, IP addresses, and mail routing configuration.

SPF Checker

Check SPF record for any domain. Validate SPF syntax, verify authorized mail senders, and detect configuration issues affecting email deliverability.

DKIM Checker

Verify DKIM selector records and check domain key configuration. Validate signature setup to improve email authentication and delivery.

DMARC Checker

Check DMARC record for any domain. Validate DMARC policy mode, reporting URIs, SPF/DKIM alignment settings, and subdomain handling configuration.

Blacklist Check

Check IP or domain against 100+ DNS blacklists (RBL/DNSBL). Free email blacklist checker to detect if your mail server is blocked and causing delivery issues.

Email Validator

Verify email address deliverability with syntax check, MX record validation, and SMTP verification. Detect disposable and invalid emails.

Header Analyzer

Parse raw email headers to trace message routing, check authentication results (SPF, DKIM, DMARC), and detect delivery delays.

Email Health

Comprehensive email health score for any domain — checks MX, SPF, DKIM, DMARC, and blacklists. Get an A-F grade with recommendations.

Network & IP

9

Port Scanner

Check open ports on any IP address online. Free port scanner to scan TCP/UDP ports, detect open, closed, and filtered states across common service ports or custom ranges.

Ping Test

Ping any website or IP address online. Free ping tool to measure round-trip time, packet loss, and network latency. Test connectivity from multiple servers.

Traceroute

Trace network route to any host online. Free traceroute tool showing each hop with IP addresses, hostnames, and response times. Diagnose routing issues and latency.

IP Geolocation

Find IP address location on the map — country, city, region, ISP, ASN, timezone, and GPS coordinates. Free IP geolocation lookup for any IPv4 or IPv6 address.

Reverse IP

Find all domains hosted on a specific IP address. Discover shared hosting neighbors and verify DNS reverse lookup configuration.

Subnet Calculator

Free CIDR calculator and subnet calculator online. Compute subnet mask, wildcard mask, network/broadcast address, usable IP range, and host count from any CIDR notation.

ASN Lookup

Look up Autonomous System Number details for any IP address or ASN. View owner, country, IP ranges, and network routing information.

What Is My IP

Instantly see your public IP address with geolocation details — country, city, ISP, and ASN. No tracking, no logs.

Internet Speed Test

Test your internet connection speed — download, upload, and ping. Measure real bandwidth performance instantly.

Web & Security

6

SSL Checker

Check SSL certificate for any domain online — certificate chain, expiration date, issuer, protocol versions. Verify if SSL is valid and properly configured.

HTTP Headers

Inspect HTTP response headers for any URL. Analyze security headers (HSTS, CSP, X-Frame-Options), caching policies, and server information.

Speed Test

Measure website loading speed — TTFB, total load time, page size, compression, and resource count. Get a performance rating for any URL.

Tech Detector

Detect technologies used by any website — CMS, frameworks, JavaScript libraries, CDN, hosting, analytics, and 40+ other technologies.

Security Score

Comprehensive security audit for any domain — HTTPS, HSTS, security headers, SSL certificate, SPF, DMARC, and DNS. Get an A-F grade.

robots.txt

Fetch and parse robots.txt for any website. Analyze crawl rules, user-agent directives, sitemaps, and detect SEO configuration issues.

Images & Media

11

Image Converter & Compressor

Convert and compress images online — PNG to JPG, WebP to JPG, HEIC to JPG, AVIF, TIFF. Quality control, resize, batch processing up to 10 files. No upload to third-party servers.

Image Resizer

Resize images online to exact dimensions with aspect ratio control. Free image resizer — choose fit mode: cover, contain, fill, inside, or outside.

Image Cropper

Crop images to custom dimensions by specifying coordinates. Precise pixel-level control for cutting images to the exact size you need.

Watermark Tool

Add text or image watermarks to images with customizable position, opacity, and style. Batch processing up to 10 files with 9 placement options.

EXIF Viewer

View image metadata — camera model, resolution, GPS coordinates, date taken, ISO, shutter speed, and color channel statistics.

Image to Base64

Encode any image to Base64 data URL for embedding in CSS and HTML. Get ready-to-use code snippets for background-image and img tags.

Placeholder Generator

Generate placeholder images with custom dimensions, background color, text, and format. Perfect for mockups, wireframes, and prototypes.

Color Palette Extractor

Extract dominant colors from any image using K-means clustering. Get HEX, RGB, and HSL values with ready-to-use CSS variables.

Blur & Pixelate

Apply Gaussian blur or pixelation effect to images. Adjust intensity with a slider for privacy masking or artistic effects.

Rotate & Flip

Rotate images by 90, 180, 270 degrees or any custom angle. Flip horizontally or vertically. Combine rotation with mirroring.

Web Optimizer

Auto-optimize images for the web — resize to max 2000px, convert to WebP format, and compress with optimal quality settings.

Text Tools

7

Text Analyzer

Count characters, words, sentences, paragraphs and lines. Character breakdown by type, reading time estimate, and average word length.

Water Checker

Analyze stop word density and water content in your text. Identify filler words that add no meaning to improve writing quality.

Word Density

Analyze word frequency and density in text. View top words, 2-word and 3-word phrases with occurrence counts and percentages.

Case Converter

Convert text between 12 case formats — UPPER, lower, Title, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and more.

Text Diff

Compare two texts side by side with line-by-line diff highlighting. See added, removed, and unchanged lines with similarity score.

Lorem Ipsum Generator

Generate Lorem Ipsum placeholder text — paragraphs, sentences, or words. Configurable count with optional classic opening.

Regex Tester

Test regular expressions online with live pattern matching. Free regex tester showing all matches with index positions, lengths, and captured groups.

Utilities

6

Base64 Encoder/Decoder

Base64 encode and decode online. Convert text to Base64 or decode Base64 strings back to plain text. View size comparison and encoding ratio.

URL Encoder/Decoder

URL encode and decode online using encodeURI and encodeURIComponent. Parse URL structure, extract query parameters, and fix encoding issues.

Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-512 hashes online. Free hash generator for any text with hash comparison and file integrity verification.

JSON Formatter & Validator

Format, validate, and beautify JSON online. Free JSON formatter with minification, structure depth analysis, key counting, and detailed error messages for invalid JSON.

Password Generator

Generate secure passwords online with customizable length, character sets, and strength meter. Free password generator with entropy score and security rating.

UUID / ULID Generator

Generate UUID v1, v4, v7, ULID, and Nano ID. Analyze existing IDs — extract timestamps, detect versions. Custom prefixes, formats, batch generation.

Free Online Network Diagnostic Tools

Everything you need to check DNS, monitor SSL certificates, scan ports, and troubleshoot network issues — in one place.

DNS Lookup & Domain Analysis

Check DNS records for any domain with our online DNS lookup tool. Query A, AAAA, MX, CNAME, TXT, NS, and SOA records instantly. Monitor DNS propagation across global servers, perform reverse DNS lookups by IP address, and verify nameserver configurations. Our WHOIS lookup reveals domain ownership, registration dates, and expiration details — essential for domain research and security audits.

Email Deliverability & Security

Diagnose email delivery issues with MX record lookup, SPF validation, DKIM verification, and DMARC policy checks. Run a blacklist check to see if your IP or domain appears on spam databases. The email health tool combines all checks into a single comprehensive report — helping sysadmins, DevOps engineers, and email marketers ensure messages reach the inbox.

Network Scanning & Monitoring

Scan open ports on any host with our online port scanner — check common ports like 22 (SSH), 80 (HTTP), 443 (HTTPS), or specify custom ranges. Run ping tests and traceroute from our servers to measure latency and discover routing paths. Use IP geolocation to identify the physical location, ASN, and ISP of any IP address. All tools work directly in your browser, no installation required.

SSL Certificate & Web Security

Verify SSL/TLS certificates, check expiration dates, and validate certificate chains with our SSL checker. Inspect HTTP response headers for security misconfigurations. Detect technologies and frameworks behind any website. Generate security scores based on HTTPS enforcement, HSTS headers, content security policies, and other best practices used by security analysts and penetration testers.

How It Works

Use our tools for free in the browser, or integrate via REST API

1

Choose a Tool

Pick from 53+ tools — DNS lookup, port scanner, SSL checker, WHOIS, ping, traceroute, image converter, and more.

2

Enter Your Target

Type a domain name, IP address, or URL. Results appear in seconds with detailed, structured output you can copy or export.

3

Automate with API

Need bulk queries? Get a free API key and integrate DNS checks, port scans, SSL monitoring, and more into your scripts and workflows.

Built For Network Professionals

Trusted by sysadmins, DevOps teams, security analysts, and web developers worldwide

Security Audits

Check SSL certificates, scan open ports, verify SPF/DKIM/DMARC records, and assess website security headers to identify vulnerabilities before attackers do.

Email Troubleshooting

Diagnose why emails land in spam. Check MX records, validate SPF and DMARC policies, look up IP blacklists, and analyze email headers to pinpoint delivery issues.

DNS Management

Monitor DNS propagation after changes, verify A/CNAME/TXT records, check nameserver configurations, and perform WHOIS lookups on any domain globally.

DevOps & Automation

Integrate all tools via REST API. Automate SSL expiry monitoring, port scanning, DNS record validation, and blacklist checks in your CI/CD pipelines and monitoring scripts.

Network Diagnostics

Run ping tests to measure latency, trace packet routes with traceroute, scan ports to find open services, and geolocate IP addresses — all from your browser.

Image & Text Utilities

Convert, resize, and optimize images online. Extract EXIF data, generate color palettes, analyze text readability, and use developer utilities like Base64, JSON formatter, and hash generators.

Frequently Asked Questions

What is a DNS lookup and how does it work?
A DNS lookup queries the Domain Name System to find records associated with a domain name. When you enter a domain, our tool queries DNS servers to retrieve A records (IPv4 addresses), AAAA records (IPv6), MX records (mail servers), CNAME records (aliases), TXT records (verification and policy), NS records (nameservers), and SOA records (zone authority). This is essential for verifying DNS configurations, troubleshooting website and email issues, and monitoring DNS propagation after changes.
How do I check if my SSL certificate is valid?
Use our SSL checker tool — enter your domain and we'll connect to your server to verify the SSL/TLS certificate. The report shows the issuer, validity dates, certificate chain, supported TLS versions, and any configuration errors. You'll see immediately if your certificate is expired, about to expire, or misconfigured. This helps prevent browser security warnings that drive visitors away from your site.
How do I scan ports on a remote server?
Enter an IP address or hostname into our online port scanner. You can check common ports (SSH 22, HTTP 80, HTTPS 443, SMTP 25, MySQL 3306) or specify custom port ranges. The scanner checks if ports are open, closed, or filtered — useful for firewall testing, security audits, and verifying that services are running correctly. No need to install nmap or other tools locally.
What is a WHOIS lookup?
WHOIS is a protocol for querying domain registration databases. A WHOIS lookup reveals who owns a domain, when it was registered and expires, which registrar manages it, and the nameservers it uses. This information is valuable for domain research, intellectual property investigations, identifying domain squatters, and contacting domain owners. Our tool queries global WHOIS servers for all major TLDs.
How can I check if my email domain is blacklisted?
Our blacklist checker queries dozens of DNS-based blacklists (DNSBLs) including Spamhaus, Barracuda, SORBS, and more. Enter your domain or IP address and we'll check each list simultaneously. If your server is listed, you'll see which blacklist flagged it and can take steps to get delisted. Regular monitoring prevents email delivery problems before they impact your business.
Is the NetVizor API free to use?
Yes, our free plan includes 1,000 API requests per month with access to all tools — DNS lookups, port scanning, SSL checks, WHOIS, ping, traceroute, email diagnostics, and more. Sign up, create an API key, and start making requests. Paid plans offer higher limits (up to 100,000 requests/month), faster rate limits, bulk endpoints, and dedicated support for production workloads.

53+

Network Tools

6

Languages

REST

API Available

Free

Forever

Trusted by Engineers

What Network Professionals Say

Used daily by sysadmins, DevOps engineers, and security teams worldwide

"Replaced my entire MXToolbox workflow. DNS lookups, email health checks, blacklist monitoring — all in one place with a clean UI and API access."

JM

James Mitchell

Sr. DevOps Engineer

"The REST API is a game-changer for our monitoring scripts. We automated SSL certificate checks and DNS propagation alerts in an afternoon."

SK

Sarah Kim

Security Analyst, CloudSec Inc

"Finally, a tool that supports multiple languages and doesn't bombard you with ads. The image tools and text utilities are a bonus I didn't expect."

RL

Ricardo Lopez

Network Administrator

No data stored
HTTPS encrypted
Open REST API
7 languages
Why NetVizor?

Compare With Alternatives

See how NetVizor stacks up against popular network tool platforms

FeatureNetVizorMXToolboxDNSCheckerWhatsMyDNS
DNS Lookup & Propagation
Email Health & Blacklist
SSL / TLS Checker
Port Scanner
WHOIS Lookup
Image & Text Utilities
REST API AccessPaid
Multi-language (7 langs)
Bulk Processing
No Ads
Free ForeverLimited
Try All Tools Free
REST API

Developer API

Every tool available as a REST API. 1,000 free requests per month.

Free tier — forever

Get Free API KeyView Documentation
curl -X POST https://api.netvizor.app/v1/dns/lookup \
  -H "Authorization: Bearer ns_key_..." \
  -d '{"target": "example.com", "type": "A"}'

// Response
{
  "status": "success",
  "data": {
    "records": [
      { "type": "A", "value": "93.184.216.34", "ttl": 3600 }
    ]
  },
  "meta": { "duration_ms": 42 }
}