How does FireShield know my bill is spiking?

Google reports each project's spend to FireShield through its budget notifications. The moment a report arrives, FireShield checks it against your thresholds and runs their actions; nobody has to read an email first. How often and how soon Google reports is up to Google.

What does it actually do when a threshold is crossed?

Whatever you set for that threshold. Every budget starts with a Hard Kill at 100% (disconnecting the project's GCP billing account so spend stops), which you can move or remove. On any threshold you can add alerts (email, Slack, Telegram) and, if you want it, a Soft Kill: a signed webhook to your own infrastructure asking it to degrade service.

Do I need to change my application code?

No. You link your project by signing in with Google, which grants FireShield an IAM role on its billing account. Nothing to install. Your code only changes if you choose to use Soft Kills: then you add one endpoint to receive the webhook. FireShield never touches your running services directly.

Can FireShield read my source code or infrastructure secrets?

No. Onboarding is zero-secrets: it uses IAM role grants, not uploaded credentials.

What's the difference between Starter, Pro and Enterprise?

All three protect your projects the same way: unlimited thresholds, email alerts, Soft Kill and Hard Kill. Starter covers one project. Pro covers up to 5 projects and adds Slack and Telegram alerts, per-project spend charts, a spend breakdown by service, and usage spike detection checked every 10 minutes. Enterprise has everything in Pro, with no limit on projects and spike checks every 5 minutes.

Does FireShield work with Firebase projects?

Yes. Firebase runs on Google Cloud, so any Firebase project on the pay-as-you-go Blaze plan is a GCP project FireShield can protect. If you've ever hit a surprise Firebase usage limit or a Blaze plan bill that got out of hand, that's exactly the scenario FireShield exists to stop.

What is usage spike detection?

Google reports spend with a delay of 15 minutes to several hours, so a runaway can grow before any budget alert fires. On Pro and Enterprise, FireShield also reads the usage of each service (Firestore, Cloud Functions, Storage, Realtime Database, Hosting, Gemini) and compares the last hour with the same hour over the last 7 days. When a service jumps past the multiplier you set, say 10 times its normal level, it runs the actions you chose: an alert, a Soft Kill or a Hard Kill. It measures usage, not cost, and you turn it on per project, which grants FireShield read-only access to that project's usage metrics.

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Bill horror story

$67,000 in 19 hours: a Firebase Android key from 2016

October 21, 2026 · 3 min read

A botnet called Gemini with an Android key Firebase had created ten years earlier, never restricted. The charges were disputed and still pending.

Retold from Google AI Developers Forum, by junghyun_colavo, April 28, 2026. Summary in our own words; every figure is the source's.

What happened

A small South Korean startup was charged around $67,000 between early April 18 and the morning of April 19, 2026 (Korean time). A botnet was calling the Gemini API with an Android API key that Firebase had created for the project back in 2016.

According to the poster, Google's May 2024 policy of automatically restricting keys like this one had never been applied to it, so a ten-year-old key could still reach an API that didn't exist when it was created.

How it ended

The first dispute was denied; the poster quotes Google support: "we are unable to make adjustments to these particular charges." It was escalated through their reseller, and as of the poster's May 23 update it was still pending with Google's root cause analysis team.

What would have stopped it

Auditing old keys. Every key a project has ever created can reach every API later enabled on it, unless it's restricted. Review the credentials page of old projects and restrict or delete what you don't use.
A quota on the expensive API. A daily request quota on Gemini bounds the damage from any key, old or new.
Spike detection with an automatic action. Gemini traffic from a botnet is a huge jump over a normal day. Detected within minutes and answered with a Soft Kill or a Hard Kill, it's a bad morning, not a $67,000 one.