TLS 1.3 + X25519MLKEM768 checker by @singe

QuantumHello

Enter a hostname or HTTPS URL to check for post-quantum encryption support. The checker proves support by offering only X25519MLKEM768 in a TLS 1.3 handshake.

Examples: cloudflare.com, https://google.com, example.com:443

Results

The results will appear here. If the target is reachable, you’ll see TLS 1.3, cipher suite, and whether the X25519MLKEM768-only handshake worked.

API usage

Use the JSON endpoint for scriptable checks.

Request:

curl 'https://your-app.fly.dev/api/check?url=cloudflare.com'

Response:

{
  "status": "supported",
  "control_probe": {
    "offered_curves": ["X25519MLKEM768", "SecP256r1MLKEM768", "SecP384r1MLKEM1024", "X25519", "CurveP256", "CurveP384", "CurveP521"],
    "negotiated_curve": "X25519MLKEM768"
  },
  "pq_probe": {
    "offered_curves": ["X25519MLKEM768"],
    "negotiated_curve": "X25519MLKEM768"
  }
}

Replace the host with any HTTPS hostname you want to check.