Monitor Website Uptime with Google Apps Script

You don't need a paid uptime monitoring service for simple projects. With Apps Script and a time-based trigger, you can check your site every few minutes and get alerted the moment it goes down.

Basic uptime check

function checkUptime() {
  const url = 'https://yourwebsite.com';

  try {
    const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
    const statusCode = response.getResponseCode();

    if (statusCode >= 200 && statusCode < 300) {
      Logger.log(`✅ ${url} is UP (${statusCode})`);
    } else {
      Logger.log(`❌ ${url} returned status ${statusCode}`);
      sendDownAlert(url, statusCode);
    }
  } catch (e) {
    Logger.log(`❌ ${url} is unreachable: ${e.message}`);
    sendDownAlert(url, 'Unreachable');
  }
}

function sendDownAlert(url, status) {
  GmailApp.sendEmail(
    '[email protected]',
    `⚠️ Site Down: ${url}`,
    `Your site ${url} appears to be down.\nStatus: ${status}\nTime: ${new Date()}`
  );
}

Log response times to a Google Sheet

function checkUptimeAndLog() {
  const sites = [
    'https://yourwebsite.com',
    'https://api.yourwebsite.com/health',
  ];

  const sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();

  // Add header row if sheet is empty
  if (sheet.getLastRow() === 0) {
    sheet.appendRow(['Timestamp', 'URL', 'Status Code', 'Response Time (ms)', 'Status']);
  }

  sites.forEach(url => {
    const start = Date.now();
    let statusCode = 'Error';
    let status = 'DOWN';

    try {
      const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
      statusCode = response.getResponseCode();
      status = statusCode >= 200 && statusCode < 300 ? 'UP' : 'DOWN';
    } catch (e) {
      statusCode = e.message;
    }

    const responseTime = Date.now() - start;

    sheet.appendRow([new Date(), url, statusCode, responseTime, status]);

    if (status === 'DOWN') {
      sendDownAlert(url, statusCode);
    }
  });
}

Avoid alert spam with cooldown tracking

Without a cooldown, you'll get an email every 5 minutes while your site is down. Use PropertiesService to track when the last alert was sent:

function checkWithCooldown() {
  const url = 'https://yourwebsite.com';
  const cooldownMinutes = 30;
  const lastAlertKey = 'LAST_ALERT_TIME';

  let statusCode;
  try {
    const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
    statusCode = response.getResponseCode();
  } catch (e) {
    statusCode = 0;
  }

  const isDown = statusCode < 200 || statusCode >= 300;

  if (isDown) {
    const props = PropertiesService.getScriptProperties();
    const lastAlert = props.getProperty(lastAlertKey);
    const now = Date.now();

    if (!lastAlert || (now - parseInt(lastAlert)) > cooldownMinutes * 60 * 1000) {
      GmailApp.sendEmail(
        '[email protected]',
        `⚠️ Site Down: ${url}`,
        `Status: ${statusCode || 'Unreachable'}\nTime: ${new Date()}`
      );
      props.setProperty(lastAlertKey, String(now));
      Logger.log('Alert sent.');
    } else {
      Logger.log('Site down, but within cooldown period. No alert sent.');
    }
  } else {
    // Reset cooldown when site is back up
    PropertiesService.getScriptProperties().deleteProperty(lastAlertKey);
    Logger.log(`✅ ${url} is UP (${statusCode})`);
  }
}

Set up a 5-minute check trigger

function createUptimeTrigger() {
  ScriptApp.newTrigger('checkWithCooldown')
    .timeBased()
    .everyMinutes(5)
    .create();
}

Tips

Apps Script triggers have a minimum interval of 1 minute — you can't check more frequently than that.
UrlFetchApp.fetch() has a timeout of around 60 seconds. If your site is just slow, it may still count as "up".
Log to a Sheet and use conditional formatting (red for DOWN, green for UP) for a simple dashboard.
Check /health or /ping endpoints rather than the homepage — they're faster and less likely to trigger unintended side effects.