Now in early access

Your AI API bill
stops here.

HardCap blocks API requests before your budget runs out. Not alerts. A hard stop.

Built for developers shipping AI apps with OpenAI, Anthropic, Gemini, and other usage-based APIs.

Join 0 developers protecting their API spend

firewall.log

→ POST /v1/chat/completions

→ model: gpt-4o · est. cost: $0.12

✗ Request blocked — budget limit reached

$20.00 / $20.00 used

→ HardCap firewall active

THE RISK IS REAL

One bug. One leaked key. One infinite loop.

That's all it takes for a bad deploy or exposed key to become a real invoice.

🔑

Exposed API key

A key in your frontend code. Someone finds it. $3,000 bill by morning.

∞

Infinite loop in prod

A while loop hits your API 10,000 times. You find out on the invoice.

🔔

Alerts aren't enough

You get an email after $500 is spent. The damage is already done.

HOW IT WORKS

Set a limit. We enforce it.

Connect your keys

Point your app at HardCap instead of OpenAI or Anthropic directly. Takes 2 minutes.

→

Set a hard budget

Define exactly how much each project or key can spend. Per day, week, or month.

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Sleep easy

When the limit is hit, requests are blocked. Not alerted. Blocked. You stay in control.

“A Firebase browser key accessed Gemini APIs without restriction. €54,000 spent in 13 hours.”

Hacker News, 307 upvotes

HardCap would have stopped this at whatever limit you set.

Never get a surprise AI bill again.