LLMBillingKit 0.1.1

Track net margin on every LLM API call

LLMBillingKit

LLMBillingKit helps you measure real profit per LLM call with one line of code and no external infrastructure.

The problem this solves

When you charge end users for AI features, your real margin can drift quickly because token pricing changes often, model mix shifts over time, and provider-specific pricing rules are easy to miss. Most teams either track only revenue or build ad-hoc spreadsheets that do not stay accurate.

LLMBillingKit gives you a local, auditable ledger of what you charged and what each request likely cost, so you can answer: "Are we making money on this feature?" in seconds.

Why local SQLite and zero infrastructure are deliberate

• Your usage and customer billing telemetry stays on your machine.
• No hosted service to provision, secure, or pay for.
• No extra API keys, webhooks, queues, or background workers.
• Works offline for local development and incident analysis.

This is a deliberate trade-off: LLMBillingKit is designed to be a lightweight embedded accounting layer, not a hosted analytics platform.

Install

pip install llmbillingkit

Quick usage

from openai import OpenAI
from LLMBillingKit import track

client = OpenAI()
response = client.chat.completions.create(
        model="gpt-4o",
        messages=[{"role": "user", "content": "Hello!"}],
)

event = track(response, charged=0.05, customer="user_123")
print(event)

track() works with OpenAI-compatible responses and Anthropic-style usage fields (input_tokens / output_tokens).

How it works

1. track(response, charged, customer) extracts model, token usage, and request_id from the response object.
2. It looks up per-token pricing from bundled costs.json.
3. It computes:

$$ \mathrm{actual_cost} = (\mathrm{input_tokens} \times \mathrm{input_price}) + (\mathrm{output_tokens} \times \mathrm{output_price}) $$

$$ \mathrm{margin} = \mathrm{charged} - \mathrm{actual_cost} $$

4. It stores the event in local SQLite (~/.LLMBillingKit/usage.db).
5. The CLI reads this table to generate reporting and exports.

If a model is unknown in the pricing table, track() returns None rather than crashing your app. Pass raise_errors=True to get an explicit TrackingError describing what went wrong:

from LLMBillingKit import TrackingError, track

try:
    track(response, charged=0.01, customer="user_123", raise_errors=True)
except TrackingError as e:
    print(f"could not track: {e}")

A small allowlist of dated provider snapshots that are verified to share pricing with a base model (for example gpt-4o-mini-2024-07-18 → gpt-4o-mini) is normalized automatically. Anthropic canonical IDs already include a date in their pricing key (claude-3-5-sonnet-20241022) and are matched as-is. Other dated snapshots — including OpenAI ones priced differently from their alias (e.g. gpt-4o-2024-05-13) — must be added to costs.json with their own prices; they will not be silently collapsed onto another model's rates.

CLI commands and sample output

llmbilling report

$ llmbilling report
Customer      Calls    Charged      Cost    Margin
----------  -------  ---------  --------  --------
acme_corp        84  $4.200000  $0.620000  $3.580000
pro_tier         47  $2.350000  $0.190000  $2.160000
trial_user       23  $0.460000  $0.310000  $0.150000
user_free       312  $0.000000  $1.870000  $-1.870000

llmbilling models

$ llmbilling models
Model                          Calls    Charged      Cost    Margin
---------------------------  -------  ---------  --------  --------
gpt-4o                           112  $0.560000  $0.094000  $0.466000
gpt-4o-mini                      289  $0.140000  $0.003000  $0.137000
claude-3-5-sonnet-20241022        65  $0.300000  $0.120000  $0.180000

llmbilling export --format csv

$ llmbilling export --format csv
request_id,timestamp,customer,model,input_tokens,output_tokens,actual_cost,charged,margin
chatcmpl-abc,2026-03-25T14:32:10+00:00,acme_corp,gpt-4o,450,120,0.00213,0.05,0.04787
msg-xyz,2026-03-25T14:33:50+00:00,pro_tier,claude-3-5-sonnet-20241022,200,80,0.00105,0.02,0.01895

llmbilling export --format json

$ llmbilling export --format json
[
    {
        "request_id": "chatcmpl-abc",
        "timestamp": "2026-03-25T14:32:10+00:00",
        "customer": "acme_corp",
        "model": "gpt-4o",
        "input_tokens": 450,
        "output_tokens": 120,
        "actual_cost": 0.00213,
        "charged": 0.05,
        "margin": 0.04787
    }
]

llmbilling add

Record a usage event without writing Python — useful for backfills, manual corrections, or providers that do not return a structured response.

$ llmbilling add \
    --customer acme \
    --model gpt-4o-mini \
    --input-tokens 8 \
    --output-tokens 9 \
    --charged 0.10
Added event:
  request_id: 6a4f...
  customer:   acme
  model:      gpt-4o-mini
  tokens:     in=8 out=9
  charged:    $0.100000
  cost:       $0.000007
  margin:     $0.099993

llmbilling update

Edit the customer or charged amount on an existing record. Margin is recomputed automatically when --charged changes.

llmbilling update --request-id chatcmpl-abc --charged 0.25
llmbilling update --request-id chatcmpl-abc --customer acme-enterprise

CLI reference

Command	Description
llmbilling report	Margin breakdown by customer
llmbilling report --days 7	Filter to the last 7 days
llmbilling report --model gpt-4o	Filter by model
llmbilling models	Margin breakdown by model
llmbilling models --days 30	Model report for the last 30 days
llmbilling export	Export raw events as CSV
llmbilling export --format json	Export raw events as JSON
llmbilling add --customer <name> --model <model> --input-tokens <n> --output-tokens <n> --charged <amount>	Record a usage event from the CLI
llmbilling update --request-id <id> --charged <amount>	Update the charged amount on an existing event (recomputes margin)
llmbilling update --request-id <id> --customer <customer>	Reassign an event to a different customer

Supported models

Pricing data lives in LLMBillingKit/costs.json and is verified in PRICING_VERIFICATION.md.

Current table includes representative models from:

• OpenAI (for example gpt-4o, gpt-4o-mini, o3-mini)
• Anthropic (for example claude-sonnet-4-20250514, claude-3-5-haiku-20241022)
• Google (for example gemini-2.5-pro, gemini-2.5-flash)
• Mistral (for example mistral-large-latest)

Limitations

• Cost accuracy depends on the bundled static pricing table and how quickly it is updated.
• Some providers have pricing nuances (for example reasoning tokens or tier-based rates) that may not be fully modeled.
• Unknown models return None from track() until their pricing is added.
• SQLite is local-first by design, so there is no built-in multi-host sync dashboard.
• test_e2e.py requires a real provider API key and network access.

Roadmap

• Faster pricing table update process and validation automation.
• Optional backends beyond local SQLite for teams that need centralized storage.
• More built-in analytics views (cohort, endpoint, and trend reporting).
• Better tooling around provider-specific pricing edge cases.

Examples

See examples/ for runnable scripts that demonstrate tracking and reporting patterns.

Contributing

Contributions are welcome. Start with CONTRIBUTING.md for setup, test, and PR guidance.

Code of conduct

This project follows the Contributor Covenant. See CODE_OF_CONDUCT.md.

Changelog

Release notes and version history are in CHANGELOG.md.

License

MIT