SpendSentry

The $34,000 bug existed for 8 days. SpendSentry would have caught it in 12 minutes.

The incident

A developer recently pushed code containing a runaway while loop generating unlimited API requests, unnoticed until they received a $34,000 bill from their cloud provider 8 days later. Cloud platforms alert you when you cross billing thresholds—often after the damage is done.

SpendSentry watches spend velocity per deployment. It connects directly to your cloud, matches spend acceleration to git commits, and alerts you the moment spend spikes relative to its usual rate.

Demo

Install

pip install spendsentry

Quick start

# Configure cloud provider + alert channel
spendsentry config --provider aws --alert telegram

# Start the daemon (monitors spend continuously)
spendsentry daemon start

# Set spend limits
spendsentry limit --daily 50 --hourly 5 --alert-at 80

Sample output

SpendSentry — Spend Monitor
──────────────────────────────────────────────────
✦ Today's spend       $4.21  (limit: $50.00)
✦ Last hour           $1.83  ⚠ HIGH — 3× normal rate
✦ Spend velocity      ↑ accelerating since 14:32

  Recent deployments:
  14:31  abc1234  feat: add image processor         $0.02 → $1.83/hr ← SPIKE
  11:20  def5678  fix: update dependencies          $0.18/hr (normal)
  09:05  ghi9012  chore: bump versions              $0.21/hr (normal)

✦ Alert sent          Telegram @ 14:34
✦ Recommendation      Roll back abc1234 or investigate image processor
──────────────────────────────────────────────────

How it works

1. Polls Cost API: Background daemon queries cloud cost (AWS Cost Explorer) every 5 minutes.
2. Calculates Velocity: Checks current rate against historical 7-day average for the same time.
3. Correlates: If a spike (>2.5x normal) is found, maps it to the nearest preceding git commit.
4. Alerts: Immediately fires a notification to Telegram, Slack, or Email.

Supported providers

• AWS ✅
• GCP 🔜
• Azure 🔜

Alert channels

• Telegram ✅
• Slack ✅
• Email 🔜

CI integration

Run a one-shot check as a deployment gate.

spendsentry check --fail-if-over 10

Configuration reference

Configuration is stored in ~/.spendsentry/config.toml. Use the CLI spendsentry config and spendsentry limit to manage settings.

Contributing / License

MIT License. Contributions welcome!

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The Developer Toolkit Ecosystem

This tool is part of a suite of open-source AI-powered developer tools built by the same team:

Tool	What it does
RootCause	Auto-diagnose failing tests — AI root cause + fix
ErrorMentor	Auto-diagnose production errors — correlate logs with git commits
TestGap	Find untested code paths after every commit
HalluCheck	Catch AI hallucinations in code diffs
IntentDiff	Understand what a diff actually does semantically
DepSecure	Block vulnerable dependencies at commit time
ArchGuard	Enforce microservice architecture rules across repos
SpendSentry	Monitor cloud spend in real time — alert before costs spiral
ContextKit	Build minimal AI context bundles — 88% fewer tokens