Track OpenAI API Cost Per User and Project
Stop guessing who burned the credits. Know your per-user, per-project API cost in real time.
The Problem: One Shared Key, Zero Visibility
Most AI products start with one shared provider API key. That is fine for a prototype, but risky in production.
Once real users arrive, you need answers to questions like:
- Which user is using the most tokens?
- Which project is driving the bill?
- Should a key stop after reaching a budget?
- Are retry loops or abuse causing unexpected bills?
- How much margin does each user or plan actually have?
With one shared key, you cannot answer any of these. And by the time the OpenAI bill arrives, it is too late.
Five Common AI Product Cost Traps
- No per-user visibility — All usage is aggregated under one key. You cannot tell which user spent what.
- No budget enforcement — Free users, trial users, and paid users all share the same key with no limits.
- Retry loop bill explosions — A failing request with auto-retry can consume thousands of tokens in minutes.
- Unclear cost boundaries — Free and paid user costs blend together, hiding your real margins.
- Retrofit pain — Adding cost tracking after launch requires rewriting auth, middleware, and billing logic.
The Solution: Gateway-Level Cost Tracking
CostLLM helps you track LLM API usage per virtual key, user, or project through an OpenAI-compatible gateway.
Your app keeps using a familiar /v1/chat/completions endpoint, while CostLLM handles:
Virtual API Keys
Usage Tracking
Budget Limits
Rate Limits
Simple Billing
OpenAI-Compatible Endpoint
No Prompt Logging
- Virtual API keys per user or project — One key per tenant. Every request is attributed.
- Token usage per key — Real-time dashboard shows exactly who is spending what.
- Hard budget limits — Set a spending cap per key. CostLLM stops requests automatically when the budget is reached.
- Rate limits — Stop abuse and retry-loop explosions before they hit your provider bill.
- Simple billing visibility — Dashboard for API keys, usage, credits, and cost per key.
- No prompt content logging — CostLLM only stores token counts and metadata needed for billing, limits, and abuse prevention. Your users' prompts stay private.
Quick Start — One Line Change
Change your base URL and API key. That's it.
curl https://api.costllm.ai/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_COSTLLM_KEY" \
-d '{
"model": "deepseek-v4-flash",
"messages": [
{
"role": "user",
"content": "Write a short onboarding email for a SaaS user."
}
]
}'
Before vs After
| Scenario |
Before CostLLM |
After CostLLM |
| Track per-user cost |
Impossible (shared key) |
Per-key dashboard |
| Set budget per user |
Manual monitoring |
Automatic hard cap |
| Stop retry-loops |
After the bill arrives |
Rate limits prevent them |
| Know free vs paid costs |
Guesswork |
Per-plan key budgets |
| Provider key security |
Exposed everywhere |
Hidden behind gateway |
Pricing Visibility from Day One
Knowing your per-user API cost is the foundation of AI product pricing:
- Set the right price — Know your cost per user before setting plan prices.
- Offer usage-based plans — Track cost per key and bill accordingly.
- Prevent abuse — Hard budget limits stop free-tier abuse instantly.
- Optimize margins — See which features, users, or projects consume the most tokens.