How to get Google Ads anomaly alerts in Slack (free script, 2026)

A free, copy-paste way to get Google Ads spend and conversion alerts in a Slack channel, with the limits you should know before you trust it.

To get Google Ads anomaly alerts in Slack, create a Slack incoming webhook, paste a Google Ads script that compares yesterday's spend and conversions with the 14 days before it, and schedule the script to run every morning. The script Thibaut sends you on LinkedIn does exactly that for free: it posts only when a number crosses your threshold, and it changes nothing in the account.

If you'd rather not keep code alive, Zapier can pass a scheduled Google Ads report to Slack, and an AI coworker such as Patricia watches Google Ads, Meta Ads and LinkedIn Ads every morning and posts each flag with its likely cause. Both are covered below.

Your options at a glance

Zapier's Google Ads triggers and actions checked on zapier.com on 3 Nov 2026. Setup times are our estimates.

What counts as an anomaly

An alert you ignore is worse than no alert. Three false alarms and people stop reading the channel, so the script flags only moves that need a person, and it only judges complete days. A half-finished "today" compared with full days always looks like a drop.

The 25% drift and the 20-conversion minimum are the defaults Patricia's own anomaly watch uses on Google Ads. Below 20 conversions a week, a CPA swing is mostly noise.

Set it up in 6 steps

Step 1. Create a Slack incoming webhook

1. Go to api.slack.com/apps, click Create New App, pick a name such as "Google Ads alerts" and your workspace.
2. Open Incoming Webhooks and switch on Activate Incoming Webhooks.
3. Click Add New Webhook to Workspace, choose the alert channel (one per client works well), then Authorize. For a private channel, you must be a member first.
4. Copy the URL. It looks like https://hooks.slack.com/services/T000/B000/XXXX.

Per Slack's webhook guide, the URL "contains a secret". Anyone holding it can post to that channel, and Slack revokes webhook URLs it finds leaked online.

Step 2. Create a new Google Ads script

In Google Ads, open Tools in the left menu, then Bulk actions, then Scripts (or search "Scripts" in the Google Ads search bar). Click the plus button to add a new script and name it "Slack anomaly alerts". The path comes from Google's getting-started guide.

Step 3. Paste the script and set your thresholds

Connect with Thibaut on LinkedIn below and he sends you the script, with the setup steps. Delete the sample code, paste the script, and put your webhook URL in SLACK_WEBHOOK_URL. Change only the constants at the top.

/**
 * Google Ads anomaly alerts in Slack: a free Google Ads script.
 * Compares yesterday with the 14 days before it, in the account's time zone,
 * and posts to a Slack incoming webhook only when a number looks wrong.
 * It reads the account and changes nothing. Test it on one account first.
 */

// Settings: change these, leave the code below alone.
var SLACK_WEBHOOK_URL = 'https://hooks.slack.com/services/XXX/YYY/ZZZ'; // a secret: do not share it
var NORM_DAYS = 14;          // days that define "normal" (keep 14 or more)
var SPIKE_PCT = 100;         // spend spike: yesterday 100% above normal, so double
var STOP_PCT = 20;           // spend stop: yesterday under 20% of normal
var MIN_NORMAL_CONV = 3;     // tracking check only when normal is 3+ conversions a day
var CPA_DRIFT_PCT = 25;      // CPA drift: last 7 days 25% worse than the 7 days before
var MIN_WEEK_CONV = 20;      // CPA check only with 20+ conversions in each week
var TODAY_SPEND_CAP = 0;     // hourly guard: alert when today's spend passes this amount (0 = off)
var DAILY_CHECK_HOUR = -1;   // on an hourly schedule, run the daily checks at this hour only, e.g. 8 (-1 = every run)
var POST_WHEN_CLEAN = false; // true also posts "Nothing unusual" (handy for your first test)

function main() {
  var account = AdsApp.currentAccount();
  var tz = account.getTimeZone();

Hi, connect with me on LinkedIn

Send me a message that says "Google Ads script" and I send you the full script with the setup steps.

Connect with Thibaut on LinkedIn

How it reads the account: one AdsApp.search query on the customer resource returns spend (metrics.cost_micros, divided by 1,000,000) and conversions per day for the last 15 complete days. Dates come from the account's own time zone through getTimeZone(), so a New York account isn't judged on a London day. A day with no row counts as zero spend, which is how the spend stop gets caught.

Step 4. Authorize, then preview

1. Click Authorize when Google asks. Each script needs this once.
2. Set POST_WHEN_CLEAN = true for the first run, so you get a message even on a quiet day.
3. Click Preview. Open Logs: you should see Slack answered 200: ok, and the message in your channel.

Preview still posts to Slack. Google's preview docs say preview only changes the behavior of calls made through AdsApp, and other services run as normal. This script makes no changes through AdsApp, so preview and a real run do the same thing. Set POST_WHEN_CLEAN back to false afterwards.

Step 5. Schedule it: daily, or hourly with a cap

On the Scripts page, set the frequency in the script's row. Google lists hourly, daily, weekly and monthly schedules (Google Ads scripts overview).

• Daily, early morning in the account's time zone. The right default. The four checks judge yesterday, and yesterday only changes once a day.
• Hourly, for accounts that can burn a budget before lunch. Set TODAY_SPEND_CAP to the most you'd accept in one day, and DAILY_CHECK_HOUR to 8 so the four daily checks post once, at 8:00, instead of every hour. The cap alert repeats each hour while spend stays above it, which is usually what you want.

Step 6. Force one test alert

Set TODAY_SPEND_CAP = 1 and click Run on an account that spent anything today. Slack should show "Today so far: ... above your cap of USD 1.00". Set the cap back to 0 or your real number. Test it on one account first, read a week of alerts, then copy it to the next client.

Where the free script stops

• One account per script. As written, it checks the account it lives in. From a manager (MCC) account, rewrite main() with AdsManagerApp to loop over client accounts, and keep the 30-minute run limit in mind.
• Yesterday, not now. The daily checks catch Tuesday's problem on Wednesday morning. Only the optional cap watches today.
• Conversions still arriving. Google Ads credits a conversion to the day of the click, so a lead that converts three days later lands on an old date. On long sales cycles, the zero-conversion check can fire early. Raise MIN_NORMAL_CONV or turn that check off.
• Double-counted conversions. metrics.conversions adds up every primary conversion action. If two primary actions fire for one sale, the CPA check works on doubled numbers. Patricia's watch counts only the conversion you name as the real result for this reason.
• Account totals only. A spike in one campaign hides inside a flat account. Swap customer for campaign in the query and group by campaign.name if you need campaign-level flags.
• No cause, no next step. The message says what moved. Someone still has to open the account and find out why.
• A paused account alerts every day as a spend stop. Pause the script when you pause the account.

Three alternatives to a script

Google Ads automated rules (free, email only)

Automated rules live under Tools, Bulk actions, Rules. Per Google Ads Help, they make account changes on a schedule (status, budget, bids) and can email you the results. They're fine when the person who should react reads email. They don't post to a Slack channel, and they don't compare a day with a trailing average the way the script does.

Zapier (paid, no spend trigger)

On 3 Nov 2026, Zapier's Google Ads app listed two triggers, New Campaign and New Lead Form Entry, and a Create Report action. No trigger fires on spend. A spend alert therefore needs a scheduled Zap: a schedule step, then Google Ads Create Report, then a filter on your threshold, then a Slack message. It works without code, uses Zapier tasks on every run, and the comparison with a 14-day average has to be built in a code or formatter step.

Patricia's Ad Anomaly Watch

Meta Ads and LinkedIn Ads alerts

Most agencies run more than Google. The script idea carries over: the Meta Marketing API's insights endpoint returns spend per day for an ad account, and LinkedIn's reporting API does the same for campaigns, so the same compare-and-post logic works with a different fetch. For Meta, our Meta Ads budget pacing guide has a free Google Sheet and Apps Script version that posts to Slack.

Keep each platform on its own. Google, Meta and LinkedIn each claim conversions the others also claim, so judge each account against its own normal and its own target, and never add their conversions together.

How we built this guide

• We wrote the script from Google's documentation and ran it against mock Google Ads objects to check the logic. We didn't run it on a live account for this page. Test it on one account first.
• Docs read on 3 Nov 2026: Google Ads scripts getting started, scripts overview, preview mode, reports, Account reference, Slack incoming webhooks, Zapier Google Ads + Slack, Google Ads automated rules.
• Patricia's checks and defaults come from her Anomaly Watch skill and its settings as they ship on 3 Nov 2026.

Thibaut Hennau

Growth Manager at Patricia. He runs Patricia's SEO, AI visibility and YouTube, and watches BetterPic's own Google Ads account with the same checks this page describes.