Location
Ashburn, United States
Within about 20 km
Domain
capstacker.io
Hosted on AWS EC2 in N. Virginia (us-east-1).
Still looking this up. This tab fills in as the answers arrive.
Network Every network on the internet has an autonomous system number (ASN). This is the one that announces this address.
AS14618Amazon
AWS · EC2 · N. Virginia
BGP prefixPrefix The block of addresses this IP is announced in to the rest of the internet. RPKI valid means the block's owner signed off on the network announcing it.
RPKI valid54.80.0.0/14
Seen by 3,283 peers
Latency Round trip for an HTTPS request from your browser to the site and back, including the server's reply time.
Live— ms
Measuring from your browser…
At a glance
Details
Network
- IPv4
- 54.81.73.103
- Reverse DNSThe hostname this address points back to (its PTR record).
- ec2-54-81-73-103.compute-1.amazonaws.com
- ASNThe autonomous system number of the network that announces this address.
- AS14618
- Operator
- Amazon.com, Inc.
- HostingFrom the provider's own published list of its address ranges.
- AWS · EC2N. Virginia (us-east-1)
- PrefixThe block of addresses announced over BGP that contains this address.
- 54.80.0.0/14
- RPKIWhether a signed record (ROA) authorizes this network to announce this prefix.
- Valid
- VisibilityHow many bgp.tools peers carry this announcement.
- 3,283 peers
- Type
- Content
- Registry
- ARIN
Location
- Country
- United States
- Region
- Virginia
- City
- Ashburn
- Coordinates
- 39.0469° N, 77.4903° W
- Accuracy
- Within about 20 km
- Time zone
- America/New_YorkUTC-5
- Local time
- 11:49
- Continent
- North America
Registration
RDAP- Registrar
- GoDaddy.com, LLC
- Registered
- Sep 16, 2025last year
- Expires
- Sep 16, 2027in 10 months
- Updated
- Aug 11, 2026
- StatusRegistry flags on the domain, such as locks that stop unauthorized transfers or changes.
- Delete lockedclient renew prohibitedTransfer lockedUpdate locked
- DNSSECDNSSEC signs DNS answers so they can't be forged on the way to you.
- Unsigned
- Name servers
- ns-1302.awsdns-34.orgns-1759.awsdns-27.co.ukns-780.awsdns-33.netns-232.awsdns-29.com
- Registrant
- Domains By Proxy, LLC
Sep 16, 2025309 days leftSep 16, 2027
Route
Finding a probe near you…
Networks crossed
Each network is an autonomous system (AS). Your traffic is handed from one to the next where they connect, following
the routes BGP advertises.
- AS16509Anthropic, PBC
- AS14618Amazon
Tracing from a probe near you with Globalping. Hop locations that its round-trip times rule out are left off the map.
Protected from spoofing
Mail that fails its checks is sent to spam under capstacker.io's DMARC policy, so forged mail doesn't reach inboxes.
- Receives mail
- Google Workspace
- Mail servers
- aspmx.l.google.comalt1.aspmx.l.google.comalt2.aspmx.l.google.com+2 more
- SPFLists the servers allowed to send mail for the domain. Receivers check it against the sending server.
- Soft-fails everything else1 of 10 DNS lookups · includes _spf.google.com
- DMARCTells receivers what to do with mail that fails SPF and DKIM: nothing (none), spam folder (quarantine) or reject.
- Quarantinesends reports
- MTA-STSRequires other mail servers to use encrypted connections (TLS) when delivering to this domain.
- Not published
- TLS reportsAsks other mail servers to report failed encrypted deliveries (TLS-RPT).
- Not requested
- BIMIA brand logo that some mail apps show next to authenticated mail from the domain.
- Not published
DNS records
TypeNameValueTTL
Acapstacker.io54.81.73.1035 min
NScapstacker.ions-1302.awsdns-34.org2 days
NScapstacker.ions-1759.awsdns-27.co.uk2 days
NScapstacker.ions-232.awsdns-29.com2 days
NScapstacker.ions-780.awsdns-33.net2 days
MXcapstacker.io1 aspmx.l.google.com5 min
MXcapstacker.io10 alt3.aspmx.l.google.com5 min
MXcapstacker.io10 alt4.aspmx.l.google.com5 min
MXcapstacker.io5 alt1.aspmx.l.google.com5 min
MXcapstacker.io5 alt2.aspmx.l.google.com5 min
TXTcapstacker.io"google-site-verification=e4bjZSI_k2dTwCZZp4Mdb1cXs9m5fBBs5UaDnAgWkeM"5 min
TXTcapstacker.io"v=spf1 include:_spf.google.com ~all"5 min
TXT_dmarc.capstacker.io"v=DMARC1; p=quarantine; rua=mailto:admin@capstacker.io"5 min
Exposure
Open ports
2 open- 80HTTP
- 443HTTPS
- Software
- nginx 1.24.0Linux KernelUbuntu
- Tags
- Outdated softwareCloud
- Possible CVEsMatched from the software versions it reports, so a server that's been patched without changing its version string can still be listed.
- CVE-2025-23419CVE-2023-44487
- Seen asHostnames Shodan has seen pointing at, or presented by, this address.
- capstacker.ioapp.capstacker.iowww.capstacker.ioec2-54-81-73-103.compute-1.amazonaws.com+1 more
From Shodan InternetDB, updated weekly.
HTTPS
Certificate
Valid- Issuer
- Let's Encrypt
- Issuing CA
- YE2
- Covers
- api.capstacker.io, app.capstacker.io, capstacker.io, www.capstacker.io
Sep 16, 202634 days leftDec 15, 2026
From Certificate Transparency logs, via Cert Spotter.
Security
C- HSTSStrict-Transport-Security makes browsers refuse plain HTTP to this site. Preloaded sites are HTTPS-only even on a first visit.
- 2 years · with subdomains
- HTTP → HTTPSWhether the plain http:// address redirects visitors to the secure one.
- Redirects
- HTTP/3The newest HTTP, over QUIC. Announced in the alt-svc header or the domain's HTTPS DNS record.
- Not announced
- CAADNS records naming the only certificate authorities allowed to issue certificates for the domain.
- Any CA may issue
- security.txtA standard file (RFC 9116) telling security researchers how to report vulnerabilities.
- Not published
Security headers 5 of 7
- HSTSpresent
- CSPmissing
- Framingpresent
- No sniffingpresent
- Referrerpresent
- Permissionsmissing
- Isolationpresent
Response
200 OK157 ms from CMHDNS lookup60 ms
200 capstacker.io157 ms
DNSConnect (TCP + TLS)Waiting for the replyFrom Cloudflare's CMH data center
Response headers
- server
- nginx/1.24.0 (Ubuntu)
- date
- Wed, 11 Nov 2026 16:49:37 GMT
- content-type
- text/html; charset=utf-8
- transfer-encoding
- chunked
- connection
- close
- vary
- Accept-Encoding
- x-frame-options
- DENY
- vary
- origin, Cookie
- x-content-type-options
- nosniff
- referrer-policy
- same-origin
- cross-origin-opener-policy
- same-origin
- x-content-type-options
- nosniff
- x-xss-protection
- 1; mode=block
- content-encoding
- gzip
- strict-transport-security
- max-age=63072000; includeSubDomains; preload
- x-frame-options
- SAMEORIGIN
- x-content-type-options
- nosniff
- x-xss-protection
- 1; mode=block
- referrer-policy
- strict-origin-when-cross-origin
Website
Page
Capstacker | Hire fractional talent. Pay when growth happens.
Hire fractional talent and service teams with equity, milestone, revenue-share, and hybrid pay. Free to join.
- Language
- English
Built with
- CloudFrom the provider's published address ranges.
- AWS · EC2 · N. Virginiaus-east-1
- Server
- nginxserver header “nginx/1.24.0 (Ubuntu)”
Tech stack
nginx 1.24.0 is past end of life
Built with Each entry says what gave it away: a response header, a cookie's name, an asset's path or file name, or markup the tool leaves in the page. Versions are checked against endoflife.date's support schedules and, for JavaScript packages, OSV's vulnerability database, which carries GitHub's security advisories.
Hosting
- AWS · EC2 · N. Virginiaus-east-1
AWS address range
Server
- nginx1.24.0on Ubuntu End of life
server header “nginx/1.24.0 (Ubuntu)” · current release 1.31.8 · support ended Apr 23, 2024
UI
- Alpine.js3.14.1
loaded from cdn.jsdelivr.net
Fonts
- Inter
from Google Fonts
How it's made
- RenderingPrerendered pages are built ahead of time and served as files. Pages rendered on each request are built by server code for every visitor. Pages drawn in the browser arrive nearly empty and depend on JavaScript, which most AI crawlers don't run. Islands are interactive parts in otherwise static HTML.
- Complete HTML888 words before any script runs
- HTML
- 109.7 KB · sent gzip-compressed
- Scripts
- 7 files · 6 inline5 from other sites
- Render-blockingPlain scripts in the page's head, without async, defer or type=module. The browser shows nothing until each one has downloaded and run.
- 1 script
Code from other sites Scripts a page loads from another domain run with the same power as its own code: they can read what visitors type and change the page. heade.rs checks what the HTML loads, not what tag managers add once they run.
- Fonts
- Google Fonts
- Consent
- Cookiebot
- Tag manager
- Google Tag Manager
- Public CDNsOpen-source packages loaded straight from a public CDN. A floating version (@3, @latest or none) can change under the site without a deploy. Without an integrity attribute, the browser can't tell if the CDN's copy was tampered with.
- @alpinejs/focus@3.14.1Integrity checkedalpinejs@3.14.1Integrity checked
- Integrity checksSubresource Integrity: the script tag carries a hash of the file, so the browser refuses it if the other site changes it. Analytics and tag manager scripts change by design and can't carry one; pinned library files can.
- 2 of 5 scripts
AI & agents
Open to AI crawlers
robots.txt lets every AI crawler in.
Crawlers
Allows allTrainingSearchOn request
They visit a page when someone asks an assistant about it. ChatGPT's, Perplexity's, Meta's and Amazon's treat robots.txt as advisory;
Anthropic's and Mistral's follow it.
OpenAIGPTBotallowedOAI-SearchBotallowedChatGPT-Userallowed
AnthropicClaudeBotallowedClaude-SearchBotallowedClaude-Userallowed
GoogleGoogle-ExtendedallowedGooglebotallowed—
Microsoft—bingbotallowed—
AppleApplebot-ExtendedallowedApplebotallowed—
Perplexity—PerplexityBotallowedPerplexity-Userallowed
MetaMeta-ExternalAgentallowedMeta-WebIndexerallowedMeta-ExternalFetcherallowed
AmazonAmazonbotallowedAmzn-SearchBotallowedAmzn-Userallowed
MistralMistralAI-TrainingallowedMistralAI-IndexallowedMistralAI-Userallowed
OthersCCBotallowedBytespiderallowedDuckAssistBotallowed
- Can cite itThe AI products that can use the site in their answers: each answers from one crawler (OAI-SearchBot for ChatGPT search, Googlebot for AI Overviews, bingbot for Copilot), and robots directives on the front page, like noindex, nosnippet and noarchive, keep some out.
- ChatGPT searchClaudePerplexityAI OverviewsGeminiCopilotMeta AISiri
Reading
- Without JavaScriptText on the front page before any scripts run: what GPTBot, ClaudeBot, PerplexityBot and most agents read. Google, Bing and Apple's crawlers run scripts.
- 888 words
- MarkdownAgents like Claude Code, Cursor and OpenCode ask for Markdown in their Accept header. It's the page without its markup, so it costs them far fewer tokens.
- Not offered
- llms.txtA Markdown file listing a site's key pages for AI tools. Coding agents read it; search crawlers mostly don't.
- Not published
- Structured dataschema.org JSON-LD in the page: facts about the site in a form machines read directly.
- Organization, WebSite, FAQPage
Tools Ways an AI agent can do things on the site, not just read it: an MCP server that apps like Claude, ChatGPT and Cursor connect to, an API catalog, packaged agent skills, a shopping profile (UCP), or tools the page offers AI in the browser (WebMCP). heade.rs looks in the official MCP Registry and the files the site publishes under /.well-known/.
Couldn't check: the site didn't answer heade.rs's requests for its agent files.