mTLS Tester — Mutual TLS Authentication

Test mutual TLS (client certificate) authentication configuration.

The mTLS Tester helps you verify mutual TLS (mTLS) configuration: the server requests a client certificate and the client presents one. The tool can act as a client with a certificate you supply, or it can guide you through testing whether a server requires and validates client certs. Use it to confirm that your API or service correctly enforces client certificate authentication, that the right CA is trusted, and that certificate validation (e.g. SAN, expiry) behaves as expected. Essential for debugging mTLS setup and for zero-trust or API security deployments.

Frequently Asked Questions

What is mutual TLS?

Both server and client present certificates; the server authenticates the client via its certificate.

When is mTLS used?

APIs, service-to-service auth, VPNs, and zero-trust architectures where client identity is required.

What do I need to test?

A client certificate and private key; the tool uses them to connect and shows whether the server accepts and validates them.

Server rejects my client cert—why?

Check CA trust, certificate validity, SANs, and that the server is configured to request and verify client certs.

Can I test without a client cert?

Yes. Connecting without a cert shows whether the server requires one (e.g. 401 or handshake failure).

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