How to get alerted when LLM API spend spikes

A retry loop or a forgotten test job can run up an AI bill for days before anyone looks. Two kinds of protection help, and they do different jobs.

Limits stop usage. Alerts tell a person.

Where a provider offers a spend limit, it's the only thing that can actually stop requests, so set one as a ceiling. Alerts catch a problem earlier and at a lower level, while there's still a choice to make. Use both.

What's worth alerting on

• Spend well above your own normal pattern, compared with the same weekday, rather than a fixed dollar figure that's either too noisy or too late.
• Budget thresholds at 80% and 100% of a monthly amount.
• A key that went quiet and started billing again, often a forgotten or leaked credential.
• Spend on a model you've never used, usually a config change nobody mentioned.
• Model retirements for models you rely on, before the date arrives.

Where alerts should go

A shared Slack or Microsoft Teams channel, plus the budget owner's email. Set a severity threshold so routine wobbles don't train people to ignore the channel.

What to expect on timing

Monitoring alerts can only act on usage the provider has reported, which can trail actual usage by minutes to many hours. Expect to hear about a spike the same day or the next, well before the invoice. That won't happen mid-request, which is why the provider's own limit is still worth having.

With TokenFront

Spend-spike and model-retirement alerts and a daily summary are on every plan, including Free. Paid plans add every other check above and budgets with 80% and 100% alerts. All of them can go to email, Slack or Teams. See supported platforms.