Check a partner certificate before it breaks a flow
Paste or drop an AS2, HTTPS or FTPS certificate, a whole chain, or an SFTP host key. You get the expiry, the chain, key strength, and the fingerprints to compare with your partner.
Runs entirely in your browser. This page's security policy blocks every network request, so nothing you paste or drop is uploaded.
Reads PEM, CER/DER and P7B certificates, and SSH public keys in OpenSSH, known_hosts or RFC 4716 format. Drop files anywhere on this box. Private keys and keystores are refused.
Want this watched for you?
Sounding monitoring checks your partners' certificates and SFTP host keys every night. It warns you 60, 30, 14, 7 and 1 days before an expiry, and as soon as a host key changes, by email, Slack or Teams. An on-prem agent covers networks that can't reach the internet.
Questions
Is my certificate uploaded anywhere?
No. Parsing, fingerprints and signature checks all run in JavaScript in your browser. The page's Content-Security-Policy sets connect-src 'none', which makes the browser block any request the page might try to send. You can confirm it in your browser's developer tools under Network.
What does it check?
Expiry against today's date, whether the certificate is valid yet, the chain order and whether each certificate is really signed by the next one, key type and size, signature algorithm, subject alternative names, key usage, and SHA-256 and SHA-1 fingerprints. For SFTP host keys it shows the key type and size and the SHA-256 and MD5 fingerprints, in the same format SSH clients and most B2B gateways display.
Why does it refuse private keys?
Checking a certificate never needs the private key, and a private key pasted into any web page should be treated as exposed. If you paste one by mistake, nothing is processed and the field is cleared.
Why is a SHA-1 or self-signed certificate not marked as an error?
Partner certificates for AS2 signing and encryption are often self-signed, and some long-running B2B links still use SHA-1. Those are worth knowing about, but they are not always wrong, so they show as notes and warnings rather than failures.
Who makes this?
Sounding is built by Myggiz Software B.V. in the Netherlands, by an integration consultant with 30 years of B2B and EDI work for European banks. It is the first of the Munetris tools for teams running B2B gateways.