CostWatch can now tell you if you're on track to blow your AWS budget

The thing that gets you isn't the day your AWS bill spikes — it's the day you open the billing console and realize you've been running hot all month.

CostWatch's new forecast endpoint solves that. For any connected account, it now returns:

• MTD spend — what you've actually spent so far this month
• Daily run rate — your average daily spend (MTD ÷ days elapsed)
• Projected end-of-month — run rate × days in month
• Status — on_track, at_risk (≥90% of budget), or over_budget

If you've set a monthly budget, the status field tells you immediately where you stand.

How it works

There's no AI here. It's arithmetic on Cost Explorer daily data:

daily_run_rate = mtd_spend / days_elapsed
projected_eom  = daily_run_rate × days_in_month

Budget gates:

• on_track — projected < 90% of budget (or no budget set)
• at_risk — projected ≥ 90% of budget
• over_budget — MTD already exceeds budget

GET /account/123456789012/forecast

{
  "account_alias": "prod",
  "mtd_spend": 183.42,
  "daily_run_rate": 18.34,
  "projected_eom": 550.20,
  "days_elapsed": 10,
  "days_remaining": 20,
  "days_in_month": 30,
  "budget": 500.0,
  "status": "at_risk",
  "month": "June 2026"
}

Why this is a paid feature

Free users get the weekly digest. Solo and Team plan users get the forecast — because the "am I going to overspend this month?" question is what converts a curious engineer into a paying customer.

You hit your HN front page, your EC2 bill spikes for a week, you open CostWatch and see "status": "at_risk". That's the moment.

The forecast endpoint stacks on the existing budget endpoint (PUT /account/{account_id}/budget). Set a budget, get a forecast. If you haven't set a budget, the endpoint still works — status is always on_track without a reference point, which is honest.

CostWatch isn't deployed yet — no domain, no production environment. That's next.