What is an LLM receipt?
Last updated 2026-08-19
An LLM receipt is a durable per-request record naming the model and configuration that actually served, the evidence that authorized any substitution, and the cost against the counterfactual of your requested model. It turns three questions from arguments into lookups: what ran, was it allowed to, and what did it save. On Finest every managed serve is assigned a receipt reference, and the fee itself is computed from receipts: 25% of proven savings, so the billing artifact and the trust artifact are the same object, verifiable at finest.so/verification.
What a receipt contains
- Served configuration
- The model and the settings that shape behavior, not just a model name.
- Authorization
- The evidence bar the substitution cleared, by reference, or the fact that the request served verbatim.
- The counterfactual
- What the request would have cost pinned to your requested model, next to what it cost.
- Durability state
- Whether the record is durably persisted, so a receipt is a fact rather than a log line that may have dropped.
Why receipts are the load-bearing artifact
Cost optimization dies of unattributable incidents. Something regresses, the substitutions are the suspect, and without per-request records the only safe action is rolling back the entire program. Receipts scope the blast radius: which requests, which configuration, which evidence version, answered in minutes.
Receipts also discipline the vendor. A fee defined as a share of proven savings is only chargeable where a receipt proves the saving, which means the vendor's revenue depends on the same artifact you audit. Incentives align because the paperwork is shared. The Request Compiler states the underlying billing law in one line: debited equals the lower of what served and what was requested, enforced in the database rather than promised in copy, which makes the worst case literally what you asked for. Abstention is receipted too: where nothing machine-checkable applies, the system serves your requested model, says so, and earns no fee.
What to demand from any vendor claiming savings
Per-request records, not monthly aggregates. A counterfactual stated against your requested model, not against the vendor's chosen baseline. Evidence referenced by version, so you can see what authorized a substitution at the time it happened. And a public way to resolve a receipt, so the claim survives the vendor's own dashboard. Aggregates flatter; receipts commit.
Questions people ask
- Is a receipt the same as request logging?
- No. Logs record what your code sent. A receipt commits the serving side: configuration, authorization, counterfactual cost, and durability, per request, in a form a third party can check.
- What does a receipt prove about savings?
- It states the cost of the serve next to the counterfactual cost on your requested model, under a named evidence version. Finest's fee is computed from exactly that difference, so unproven savings are unbillable by construction.
- Can I verify a Finest receipt myself?
- Yes. Receipt references resolve at finest.so/verification.
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No model markup. You pay the host’s rate. 25% of what it proves it saved on a request. No saving, no fee.