What is usage attestation?

Usage attestation is the process of signing and chaining AI usage events (tokens, API calls, compute) so they can be independently verified by any party — without relying on a vendor's self-reported data. Cost is derived separately from a declared pricing table.

How does Proof Meter work?

Your agent calls an API. ProofMeter captures the usage metadata (provider, model, tokens, timestamp). It hashes and signs the event, chains it to the previous receipt, and returns a verifiable receipt immediately. Cost is estimated separately using a declared price book.

What kinds of events can Proof Meter attest?

Any billable event — LLM API calls, vision inference, search queries, compute jobs, data transfers, or any metered service. Proof Meter is format-agnostic.

Does Proof Meter require blockchain?

No. Proof Meter uses a Merkle chain stored in Postgres with ed25519 signatures. Blockchain anchoring is on the roadmap but not required for strong tamper-evidence.

Ed25519 signed receipts Built into benchd harness

Stable usage proof
for AI spend.

ProofMeter signs what an AI system used, then lets authorized parties apply the right cost view — public estimates, private contract rates, usage-only mode, or future invoice reconciliation.

Open Explorer → Read the spec

*Estimated spend is derived from a declared price book. Actual billed cost requires invoice reconciliation.

proofmeter demo run

benchd run reliability --adapter verifiedstate --budget 5.00

✓ budget authorized under public_estimate price book

✓ 294 usage events recorded

✓ 294 receipts signed

✓ settlement Merkle root generated

✓ run verified

Estimated spend*: $3.81

Invoice reconciled: false

294

signed receipts

$3.81*

public estimate

valid

settlement proof

EVENTS

METER

$0.00

VERIFIED

How It Works

Three steps. Zero trust assumptions.

Ed25519 signed · hash-chained · Merkle-settled

{ }

Step 1

Instrument

Add one SDK call after any billable event. Capture provider, model, tokens, cost.

typescript

import { ProofMeter } from 'proofmeter';

const receipt = await meter.spend({
  provider: 'openai',
  model: 'gpt-4o',
  tokens: 2560,
  cost: 4.2,
});

Step 2

Attest

ProofMeter hashes, signs, and chains the receipt. Each receipt links to the previous one, making the chain tamper-evident.

json

{
  "receipt_id": "rcpt_7f3a",
  "hash": "sha256:e3b0c44",
  "signature": "ed25519:Mj7k",
  "status": "verified"
}

✓

Step 3

Verify

Anyone can verify any receipt at any time. No vendor trust required.

bash

$ proofmeter verify rcpt_7f3a

✓ Signature valid (ed25519)
✓ Merkle chain intact
✓ Verified at 2026-04-03

Trust Boundaries

What a receipt proves and does not prove

What a receipt proves

✓ Resource usage was recorded in a structured event

✓ The receipt payload matches its hash and signature

✓ The receipt chain and sequence are intact

✓ The declared price book hash matches the valuation

✓ The settlement total matches the included receipt set

What it does not prove by default

— The provider's internal bill unless invoice data is reconciled

— The customer's private contract rates unless an authorized price book is applied

— Provider-side attestation unless the provider signs its own usage response

— Regulatory compliance by itself; receipts are evidence, not a compliance program

— Actual billed cost until reconciliation is connected

Full trust boundaries documentation →

The protocol is open.

ProofMeter is the native spend attestation layer inside benchd-harness. Install the harness, run a benchmark with --budget, and get signed usage receipts automatically.

Read the spec → Open Explorer

pip install proofmeter · Documentation · GitHub

Patent Pending

Stable usage prooffor AI spend.

Stable usage proof
for AI spend.