TLS Checker

Overview

A TLS checker API for testing a server's TLS version support from code, a cron job or a CI pipeline, with the answer in seconds. TLS Checker connects to the domain and port you give it and runs a separate handshake at each protocol version, so it reports exactly which of TLS 1.0, 1.1, 1.2 and 1.3 are accepted. From the handshake at the highest version it returns the negotiated cipher, whether that cipher has forward secrecy, and whether the certificate validates for the host. It flags deprecated TLS 1.0/1.1, returns a composite risk score, and assigns an A+ to F grade using APIVerve's own documented rubric: TLS 1.2 or newer and a valid certificate are required; TLS 1.0/1.1, or a chosen cipher without forward secrecy or AEAD, caps the grade at B; A+ needs TLS 1.3. It does not enumerate every cipher suite or test for named vulnerabilities, so the grade is not an SSL Labs grade.

Live Test TLS Checker API →

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

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curl "https://api.apiverve.com/v1/tlscheck?domain=amazon.com&port=443" \
  -H "x-api-key: your_api_key_here"

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const res = await fetch('https://api.apiverve.com/v1/tlscheck?domain=amazon.com&port=443', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);

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import requests

res = requests.get(
    "https://api.apiverve.com/v1/tlscheck?domain=amazon.com&port=443",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])

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package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/tlscheck?domain=amazon.com&port=443", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

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{
  "status": "ok",
  "error": null,
  "data": {
    "domain": "amazon.com",
    "tlsVersions": {
      "TLSv1": false,
      "TLSv1.1": false,
      "TLSv1.2": true,
      "TLSv1.3": true
    },
    "highestVersion": "TLSv1.3",
    "negotiatedCipher": "TLS_AES_256_GCM_SHA384",
    "forwardSecrecy": true,
    "certificateTrusted": true,
    "certificateError": null,
    "hasDeprecatedTLS": false,
    "isSecure": true,
    "riskScore": 0,
    "riskLevel": "low",
    "grade": "A+",
    "gradeReasons": []
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

Use cases

Payment Gateway Auditing

Before onboarding merchant checkout domains, fintech compliance auditors check whether incoming endpoints accept legacy protocols like TLS 1.0 or 1.1.

Deployment Pipeline Verification

Flag outdated web server configurations during production releases by testing handshake support across all modern protocol versions before traffic switches over.

Attack Surface Scanning

Security analysts query customer-facing domains periodically to find legacy protocol support and review the highest negotiable version across exposed web ports.

Vendor Security Assessments

When evaluating SaaS suppliers, procurement teams inspect external hostnames to confirm that partner servers negotiate TLS 1.2 or 1.3.

Other ways to use TLS Checker

Set up TLS Checker on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Related

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