LLM cost control: token budgets and spend alerts

AI infrastructure costs can spiral without visibility. Token budgets, per-key spend caps, and real-time alerts give engineering and finance teams the levers they need to keep LLM costs predictable.

// TL;DR

LLM billing scales with prompt and response length at runtime — a 2,000-token system prompt sent 100,000 times/month costs €200–3,000 depending on the model.
Intellixer assigns per-key monthly spend caps with alerts at 50%, 80%, and hard-stop at 100% — preventing runaway costs without code changes.
Small open-source models cost ~€0.10–0.20/Mtok on Intellixer vs €2–15/Mtok for frontier models — right model selection can cut costs 10–100×.

Why AI Costs Spiral

LLM billing is fundamentally different from traditional API pricing. A REST call to a weather API costs the same every time. An LLM call costs proportionally to the length of the prompt and the response — and both are determined at runtime by user input and model behaviour, not by you.

Add multiple teams, multiple models, and a product that surfaces AI to end users, and monthly costs become unpredictable. A single poorly-written prompt that sends an entire database record to a model can cost 50× more than intended. A runaway loop in a background job can exhaust a monthly budget in hours.

How Token Billing Works

Providers charge for input tokens and output tokens separately. Input tokens include your system prompt, conversation history, and user message. Output tokens are the model's response. Prices vary significantly:

Fast, small models: ~€0.10–0.20 per million input tokens
Mid-tier models: ~€0.40–0.80 per million input tokens
Frontier models: €2–15 per million input tokens

System prompts that repeat on every call are a common cost leak. A 2,000-token system prompt sent 100,000 times per month costs €200–3,000 depending on the model — before a single word of user input.

Spend Caps and Alerts

Intellixer gives each API key a configurable monthly spend cap. When a key's cumulative spend approaches the cap, the platform sends an email alert at 80% and hard-stops calls at 100%. This prevents runaway costs at the key level without requiring application code changes.

Per-key budgets — assign a budget to each team, product feature, or environment (prod vs staging)
Real-time spend dashboard — see token consumption and cost broken down by key, model, and time window
Alert thresholds — configurable at 50%, 80%, and 100% of budget
Proforma invoicing — receive a cost projection at mid-month so finance teams are never surprised

Start Saving

Intellixer's token packages start at €10 and include full spend visibility, per-key caps, and email alerts out of the box. No configuration required.

Request early access →

// FAQ

          How much do small models cost per million tokens?
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Approximately €0.10–0.20 per million input tokens via Intellixer; mid-tier models cost ~€0.40–0.80/Mtok; frontier models cost €2–15/Mtok.

          How do I set a spending limit on an LLM API?
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Intellixer assigns each API key a monthly spend cap; email alerts fire at 80% and calls hard-stop at 100% — no application code changes required.

          Why are LLM API costs unpredictable?
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Unlike REST APIs, LLM billing is proportional to prompt and response length at runtime; repeated system prompts, runaway background jobs, and multi-model architectures all compound unpredictability.

          What is a token in LLM pricing?
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Roughly 4 characters of English text; providers charge separately for input tokens (system prompt + conversation history + user message) and output tokens (the model's response).