DNS records
A and AAAA records with TTL, geolocation for the first address, the remaining records grouped for expansion, and one-click copy for any IP.
Browser extension
TCPLab Browser Extension
DNS, WHOIS and SSL/TLS for the page you are on — in a side panel, without copying links or switching tabs.
v0.2.1 · Updated 2026-10-20 · 216 KiB
Source on GitHub
What it shows
It reads the page you are on — there is no separate lookup form.
WHOIS details
Registrar, creation and expiry dates, domain age, name servers, DNSSEC status and readable domain statuses.
SSL / TLS
Certificate subject and issuer, validity, SANs, public key, TLS version, cipher, ALPN, HTTP/2, forward secrecy and the connected IP.
Quick site grade
An S/A/B/C/D/F grade and a 0–100 score based on the certificate, HTTPS/TLS, HTTP/2, IPv6, DNSSEC and domain data. An invalid certificate caps the grade at C; missing data is marked as a partial score.
Built for the sidebar
Click the toolbar icon to open a right-side panel. No navigation, no new tab. For HTTP pages, TCPLab checks port 443 and explains it in the UI.
Three steps
- 01
Open any public page
Only public http:// and https:// pages are supported. Private and local addresses are never sent.
- 02
Click the toolbar icon
Pin TCPLab to the toolbar from the extensions menu the first time.
- 03
Read the side panel
DNS, WHOIS and certificate details in one place. Click the icon again or × to close.
Supported browsers
- Available
Chrome
Install from the Chrome Web Store
- Available
Edge and other Chromium browsers
Install the same Chrome build
- Coming soon
Firefox
Under review. This section will update when it ships.
Permissions and data
Privacy policyCurrent tab hostname
Read only when you open the panel, then sent with the DNS-resolved IPs for the lookup.
No page data uploaded
No full URL, query string, page content, cookies or browsing history.
Local addresses filtered
Private and local addresses are removed before any request is made.
Frequently asked questions
Chrome users can install it from the Chrome Web Store. Edge, Brave, Opera and other Chromium browsers can install the same Chrome build. The Firefox version is under review.
No. It reads only the current tab's hostname when the panel is open. Page content, cookies, browsing history, the full URL and query strings are never sent, and the page title stays inside the extension.
It is free and requires no sign-up.
No. It is a lightweight heuristic based on the data already loaded, useful for spotting obvious issues. It is not a replacement for a penetration test or security audit.
The extension works on public http:// and https:// pages only. Private addresses, localhost, browser-internal pages and some protected pages are filtered out. For HTTP pages it checks port 443 instead.
Network checks, right in your browser
Install the extension and inspect any page's DNS, WHOIS and certificate on the spot.
Need a fuller domain report? Run the domain check