Domain Expiration
Days remaining before a domain's registration expires.
Monitor this automatically
NetTests can run this check on a schedule, preserve historical results, compare changes over time, and alert you the moment something breaks.
Start monitoring free → See all monitoring productsFrequently Asked Questions
What does this check?
It looks up the domain's WHOIS registration record and reports how many days remain before the registration expires. An expired domain stops resolving — email bounces and the website goes offline — and the name can become available for anyone to register.
Why is days_until_expiry sometimes missing?
Some registries redact the expiration date in public WHOIS output (privacy regulations vary by Top-Level Domain (TLD)), or return a format this tool couldn't parse. When that happens the field is left blank rather than guessed — check the registrar's own portal directly.
How is this different from Whois?
Whois is the full raw registration record — every field the registry returns, plus Internet Protocol (IP)/Autonomous System Number (ASN) lookups. This tool is the same underlying domain data, narrowed to just the expiration question, so it's simple to set thresholds on in a monitor.
Network Tools
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HTTP Request
Send HyperText Transfer Protocol (HTTP) requests with custom method, headers, body, and authentication — inspect the full response.
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HTTP Request Timing
Load a Uniform Resource Locator (URL) in headless Chromium and stream every fetched resource with size and timing.
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HTTP Quick Check
The simplest possible check: fetch the page, confirm it returns 2xx.
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CORS Tester
Test any Uniform Resource Locator (URL) for Cross-Origin Resource Sharing (CORS) with a custom method, headers, and body — see exactly why a browser would allow or block the request.
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Dead Link Checker
Crawl a website and find broken internal links — renders JavaScript (JS) pages with a headless browser.
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IP Blacklist Check
Check an IPv4 address against 49 major Domain Name System (DNS) blacklists (Spamhaus, SORBS, Barracuda, SpamCop, etc.).
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Network Path Monitor
Continuous traceroute with per-hop loss and Round-Trip Time (RTT) statistics.
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Traceroute
Trace the path packets take to a destination host, hop by hop.
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Ping Scanner
Ping many hosts in parallel and report which are alive.
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Ping Host
Send Internet Control Message Protocol (ICMP) echo requests and report round-trip time (RTT) and packet loss.
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IP Geolocation
Resolve a domain or Internet Protocol (IP) address to its city, country, Autonomous System Number (ASN)/org, and coordinates — with a map.
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IPv4 ↔ IPv6
Convert IPv4 to/from IPv4-mapped IPv6 (::ffff:a.b.c.d).
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MAC OUI Lookup
Look up a Media Access Control (MAC) address's first 3 octets in the IEEE Organizationally Unique Identifier (OUI) vendor database (curated subset).
Email / SMTP Diagnostics
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Email Health
One-click domain scorecard — Blacklist, Mail Server, Web Server, and Domain Name System (DNS) checks graded Errors / Warnings / Passed, MXToolbox-style.
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Email Records Check
Consolidated Mail Exchange (MX), Sender Policy Framework (SPF), Domain-based Message Authentication, Reporting & Conformance (DMARC), and DomainKeys Identified Mail (DKIM)-selector lookup for an email domain.
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SPF Record Checker
Look up and validate a domain's Sender Policy Framework (SPF) Text (TXT) record.
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Email Blacklist Check
Resolve a domain's Mail Exchange (MX) hosts to Internet Protocol (IP) addresses and check each against 49 IP blacklists plus the domain itself against 9 domain blacklists.
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SMTP Banner Probe
Connect to a Simple Mail Transfer Protocol (SMTP) server, capture its banner + EHLO capabilities, and test STARTTLS.
Packet Generation & Testing
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TCP/UDP Connection Tester
Check Transmission Control Protocol (TCP) port reachability; optionally send a payload and read the reply.
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TLS Handshake Inspector
Inspect a server's Transport Layer Security (TLS) handshake: version, cipher, Application-Layer Protocol Negotiation (ALPN), full cert chain.
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HTTP Availability Check
Probe a list of hostnames (max 16) for HyperText Transfer Protocol (HTTP) and HyperText Transfer Protocol Secure (HTTPS) availability.
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HTTP Latency
Send N HyperText Transfer Protocol (HTTP) HEAD requests to a Uniform Resource Locator (URL) and report min/median/mean/max/stddev latency. From this server's vantage.
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Path MTU Probe
Discover the path Maximum Transmission Unit (MTU) to a host by sending increasingly large pings with the Don't Fragment (DF) bit set (binary search).
IP & Subnet Utilities
Routing & BGP
TLS / SSL Auditing
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TLS/SSL Quick Scan
Probe which Transport Layer Security (TLS) protocol versions a server accepts and show the cipher each negotiates.
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TLS/SSL Deep Scan
Full chain validation, Online Certificate Status Protocol (OCSP) stapling, Signed Certificate Timestamp (SCT) count, and per-Transport Layer Security (TLS)-version cipher matrix.
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TLS/SSL Certificate Expiration
Days remaining before a server's Transport Layer Security (TLS) certificate (and its full chain) expires.
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Domain Certificate Audit
Search Certificate Transparency logs for every Secure Sockets Layer (SSL) certificate ever issued to a domain — reveals subdomains, issuers, and historical issuance.
HTTP/2 & WebSocket
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HTTP/2 Probe
Negotiate HTTP/2 via Application-Layer Protocol Negotiation (ALPN) and decode the server's SETTINGS frame (window size, max streams, etc.).
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WebSocket Probe
Send a WebSocket Upgrade handshake and verify the Sec-WebSocket-Accept response, subprotocols, and extensions.
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HTTP/2 Stress Testerlogin
Benchmark HTTP/2 server performance — measure requests per second, latency distribution, and concurrent stream throughput under sustained load.
Encoding & Conversion
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Hex ↔ Text
Convert UTF-8 text to a hex string, or parse a hex string back to text (separators :/.- ignored).
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Binary ↔ Text
Convert UTF-8 text to 8-bit binary, or parse a binary string back to text.
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Case Converter
Convert text between common casings: UPPER, lower, Title, snake_case, kebab-case, camelCase.
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Number Base
Convert a number between decimal, binary, octal, and hexadecimal representations.
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Unix Timestamp
Convert between Unix epoch seconds and International Organization for Standardization (ISO)/Request for Comments (RFC) datetime formats (Coordinated Universal Time (UTC)).
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IPv4 ↔ Decimal
Convert between dotted IPv4 notation, 32-bit decimal, hex, and dotted binary.
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JWT Decoder
Decode a JSON Web Token (JWT) into its header and payload (no signature verification — that needs the signing key).