API Reference

Getting Started

Up and running in three steps.

POST https://apisentinel.io/api/v1/validate
x-api-key: as_live_xxxxxxxxxxxxxxxxxxxx
Content-Type: application/json

{
  "url": "https://api.example.com/health",
  "checks": {
    "statusCode": { "expected": 200 },
    "responseTiming": { "maxMs": 1000 }
  }
}

POST https://apisentinel.io/api/v1/monitors
x-api-key: as_live_xxxxxxxxxxxxxxxxxxxx
Content-Type: application/json

{
  "name": "Production API",
  "url": "https://api.example.com/health",
  "alert_email": "you@example.com"
}

Authentication

All API requests must include your API key in the x-api-key header. API keys are scoped to your account — all monitors and usage logs are isolated per key.

// Include this header on every request
x-api-key: as_live_xxxxxxxxxxxxxxxxxxxx

Error responses

Missing or invalid keys return a 401 with one of:

{ "error": "Missing x-api-key header" }

{ "error": "Invalid or inactive API key" }

Validate an endpoint

Sends a one-off request to any URL and returns a structured health report. Checks are optional — omit any you don't need. Results are logged to your account's usage history.

Request body

Request example — GET with checks

{
  "url": "https://api.example.com/health",
  "method": "GET",
  "headers": {
    "Authorization": "Bearer token123"
  },
  "checks": {
    "statusCode": {
      "expected": 200
    },
    "responseTiming": {
      "maxMs": 1000
    },
    "ssl": {
      "enabled": true,
      "minDaysRemaining": 30
    }
  }
}

Request example — POST with body

Use the body field to send a request body. Pass it as a stringified JSON string.

{
  "url": "https://api.example.com/users",
  "method": "POST",
  "headers": {
    "Authorization": "Bearer token123",
    "Content-Type": "application/json"
  },
  "body": "{"name": "Alice", "email": "alice@example.com"}",
  "checks": {
    "statusCode": {
      "expected": 201
    },
    "responseTiming": {
      "maxMs": 2000
    }
  }
}

Response — 200 OK

{
  "url": "https://api.example.com/health",
  "timestamp": "2026-05-09T12:00:00.000Z",
  "passed": true,
  "durationMs": 243,
  "statusCode": 200,
  "checks": [
    {
      "name": "status_code",
      "passed": true,
      "message": "Status code 200 is as expected",
      "details": {
        "statusCode": 200,
        "expected": [200]
      }
    },
    {
      "name": "response_timing",
      "passed": true,
      "message": "Response time 243ms is within the 1000ms limit",
      "details": {
        "durationMs": 243,
        "maxMs": 1000
      }
    },
    {
      "name": "ssl",
      "passed": true,
      "message": "SSL certificate valid, 187 days until expiry",
      "details": {
        "valid": true,
        "expiryDate": "2026-11-12T00:00:00.000Z",
        "daysRemaining": 187,
        "issuer": { "O": "Let's Encrypt" },
        "subject": { "CN": "api.example.com" }
      }
    }
  ]
}

Response — check failure

When one or more checks fail, passed is false and the failing check carries a descriptive message. The HTTP status is still 200 — the status code reflects the API call, not the target.

{
  "url": "https://api.example.com/health",
  "timestamp": "2026-05-09T12:00:00.000Z",
  "passed": false,
  "durationMs": 1847,
  "statusCode": 200,
  "checks": [
    {
      "name": "status_code",
      "passed": true,
      "message": "Status code 200 is as expected",
      "details": { "statusCode": 200, "expected": [200] }
    },
    {
      "name": "response_timing",
      "passed": false,
      "message": "Response time 1847ms exceeded the 1000ms limit",
      "details": { "durationMs": 1847, "maxMs": 1000 }
    }
  ]
}

Create a monitor

Registers an endpoint for continuous monitoring. The cron runner checks all active monitors on schedule and sends an email alert to alert_email whenever a monitor transitions from passing to failing.

Request body

Request example

{
  "name": "Production API",
  "url": "https://api.example.com/health",
  "method": "GET",
  "interval": "5m",
  "checks": {
    "statusCode": {
      "expected": 200
    },
    "responseTiming": {
      "maxMs": 2000
    },
    "ssl": {
      "enabled": true,
      "minDaysRemaining": 14
    }
  },
  "alert_email": "you@example.com"
}

Response — 201 Created

{
  "monitor_id": "550e8400-e29b-41d4-a716-446655440000",
  "status": "active"
}

List monitors

Returns active monitors associated with your API key, ordered by creation date descending. Deactivated monitors are excluded by default.

Query parameters

Response — 200 OK

{
  "monitors": [
    {
      "id": "550e8400-e29b-41d4-a716-446655440000",
      "name": "Production API",
      "url": "https://api.example.com/health",
      "method": "GET",
      "interval": "5m",
      "is_active": true,
      "alert_email": "you@example.com",
      "checks": {
        "statusCode": { "expected": 200 },
        "responseTiming": { "maxMs": 2000 }
      },
      "created_at": "2026-05-09T12:00:00.000Z"
    }
  ]
}

Get a monitor

Returns a single monitor along with its 20 most recent check results. Use this to inspect historical pass/fail status and response times.

Path parameters

Response — 200 OK

{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "name": "Production API",
  "url": "https://api.example.com/health",
  "method": "GET",
  "interval": "5m",
  "is_active": true,
  "alert_email": "you@example.com",
  "created_at": "2026-05-09T12:00:00.000Z",
  "recent_checks": [
    {
      "id": "abc12300-0000-0000-0000-000000000001",
      "status_code": 200,
      "response_time": 243,
      "passed": true,
      "created_at": "2026-05-09T12:05:00.000Z"
    },
    {
      "id": "abc12300-0000-0000-0000-000000000002",
      "status_code": 503,
      "response_time": 4821,
      "passed": false,
      "created_at": "2026-05-09T12:00:00.000Z"
    }
  ]
}

Response — 404 Not Found

{ "error": "Monitor not found" }

Deactivate a monitor

Sets the monitor's is_active flag to false — the monitor will no longer run scheduled checks or send alerts. The record and its full check history are preserved in the database; nothing is permanently deleted. To reactivate a deactivated monitor, contact support.

Path parameters

Response — 200 OK

{ "status": "deactivated" }