JPKCom DB

DNS, SSL, Redirect & URL

Check DNS and mail security, inspect SSL chains even for broken certificates, trace redirects, parse URLs, build SPF records and count lookups recursively.

Five network tools in one toolbox

DNS, SSL, Redirect & URL bundles the everyday diagnostic tasks around domains, certificates, and addresses into a single interface. Instead of hunting down a separate online tool for each step, you switch between five tabs: DNS (query DNS records and mail security), SSL / Security (inspect certificate, chain, TLS, and security headers), Redirect (trace redirect chains), URL (parse addresses and generate slugs), and SPF (build, load, and count an SPF TXT record).

It is built for everyone who works with websites and mail servers: developers who quickly need to see where a domain points or whether a certificate is about to expire; admins checking redirects and DNS entries after a migration; and SEO and email folks who need clean redirects, valid SPF records, and correct security headers. No account, no install — everything runs right in the browser.

What the five tabs check

  • DNS — queries a single record type for a domain (A, AAAA, MX, NS, TXT, CNAME, SOA, SRV, CAA, PTR, NAPTR), or runs Check All for the most important types at once plus extra checks: www, DMARC, DKIM (21 common selectors), MTA-STS, TLS-RPT, BIMI, and wildcard. The result includes a "Mail & domain security" summary card that rates SPF, DMARC, DKIM, MX, MTA-STS, TLS-RPT, BIMI, and CAA with status badges. Enter an IP address and the tool automatically switches to a reverse lookup (PTR). Output as JSON or as a BIND-style zone file.
  • SSL / Security — fetches an https:// address and breaks down the certificate: common name, issuer, validity with days remaining, key and signature, serial number, SHA-256 fingerprint, host name coverage, trust status, and the Subject Alternative Names (SANs). It shows the certificate chain exactly as the server sends it, with a signature check for every link — even for expired, self-signed, or otherwise broken certificates. On top come the TLS version and cipher, a CAA comparison, a list of findings, and a check of nine security headers. Download the chain as PEM or open it in the PKI Viewer with one click.
  • Redirect — follows a URL hop by hop (up to 10 hops), showing the status code, IP, HTTP/HTTPS flag, server, timing, certificate days remaining, and raw headers for each stop. Loops are detected; servers that refuse HEAD are queried with GET instead.
  • URL — parses an address client-side into its components (protocol, host, port, path, query parameters, hash …), shows internationalized hosts in both Unicode and Punycode, and includes a URL slug generator that turns text into clean, URL-safe slugs live (including German umlaut handling).
  • SPF — interactively builds a valid v=spf1 TXT record: all-policy, your own mail servers, 16 preconfigured providers, custom include: and IP entries. Live counters for DNS lookups and record length warn you before you hit the SPF limits. Load pulls an already published record into the form, and Count all lookups counts the DNS lookups recursively across every nested include:.

Architecture: server-side fetch, client-side analysis

Three of the tools need data from the network that a browser is not allowed to fetch itself (CORS, foreign TLS connections). That is why DNS, SSL, and Redirect work through the JPKCom servers:

  • The DNS tab sends its query to a server-side PHP endpoint that resolves the records with native PHP (dns_get_record). The recursive SPF analysis from the SPF tab runs through the same endpoint.
  • SSL and Redirect run through a server-side cURL proxy that fetches the target and returns the raw data (headers, certificate, hop chain) as JSON; the formatting and display then happen in your browser. For the SSL check, the server also opens a second TLS handshake to the same host without certificate verification — the only way to show the chain when the normal, verifying connection fails on the certificate.

These server endpoints (p.php for the fetch proxy, p-api.php for token issuance, plus the DNS endpoint) are not a public API you can call yourself: they are protected by a daily-rotating token, a time-window check, and a referer check, and are used exclusively by the tool's JavaScript. What matters in practice:

  • Privacy: the checked domain sees a request from the JPKCom server, not your IP address.
  • SSRF protection: private, local, reserved, and CGNAT addresses are blocked — for DNS reverse lookups, for the SSL/redirect fetch, and for redirects on every single hop. Only http/https on ports 80, 443, 3000, 5000, 8000, 8008, 8080, and 8443 are allowed.
  • Limits: at most 10 redirect hops with a 24 s time budget for the whole chain, 15 s for the SSL fetch, a client-side throttle of about 1 request per second, and server-side limits per IP address.

The URL parser, the slug generator, and assembling the SPF record need no server at all — they compute entirely in your browser. Only Load and Count all lookups in the SPF tab query the DNS endpoint.

Try it now

→ Open DNS, SSL, Redirect & URL — pick a tab, enter a domain or URL, read the result. No account, free, right in the browser. The DNS, SSL / Security, Redirect, and URL tabs each keep their own history of up to 20 entries (stored locally in your browser): one click puts an earlier input back into the field, and another click on the check button runs the query again.

  • SEO & GEO Analyzer — checks a whole page, including HTTPS, redirects, security headers, and performance; ideal when, after the technical check, you want the big picture.
  • PKI Viewer — inspect certificates, CSRs, and keys in detail; the PKI Viewer button hands the chain from the SSL tab straight over.
  • IP Tools — analyze IP addresses and subnets to match the DNS and redirect IPs.
  • Mail Header Analyzer — read email headers when you verify the record built in the SPF tab in real-world mail.

The subpages go deeper: the Manual with every tab and all operating limits, real-world Examples, and collected Tips & Tricks.