What it is

OpenMeter is open-source monetization infrastructure built for AI, API, and usage-based products. It lives in the Go cloud infrastructure ecosystem and uses an Apache-2.0 license. The project turns high-volume events into real-time usage, supports access enforcement, and handles usage-based billing from pricing and subscriptions through credits and invoices.

The concrete problem is that products with usage-based or hybrid pricing need one source of truth for consumption. OpenMeter ingests CloudEvents, attributes usage to customers, aggregates it in real time, and exposes queries by time window or dimension. It also models versioned plans, features, add-ons, and several price types, then assigns customer subscriptions.

Key capabilities

• Meter usage by ingesting CloudEvents, attributing events to customers, aggregating them in real time, and querying them by time window or dimension.
• Model products and pricing with versioned plans, features, add-ons, and flat, recurring, per-unit, tiered, package, or dynamic prices.
• Control access by calculating feature access and usage-limit balances, with one-time or recurring entitlement grants for the application to enforce.
• Bill usage by rating flat and usage-based charges, managing customer credit balances and subscription changes, and running the invoice lifecycle.
• Integrate through the OSS REST API and JavaScript, Python, or Go SDKs, send webhooks, and connect external invoicing providers.

Who uses it and how

• AI, API, and usage-based product teams use it as the source of truth for consumption when pricing depends on measured activity.
• Teams with prepaid credits or usage limits use it to calculate entitlement balances and let their application enforce access decisions.
• Platform teams use the REST API and SDKs to send CloudEvents, query meters, receive webhooks, and connect external invoicing providers.

Getting started

The local evaluation stack requires Git and Docker with Compose, and the quickstart clones the repository, changes to openmeter/quickstart, and runs docker compose up -d --wait. Examples can use curl, Node.js 22+, or Python 3.9+ to send one request event and query the metered value.

When to use it — and when not to

OpenMeter fits products with usage-based or hybrid pricing, prepaid credits, or usage limits that need one source of truth for consumption. It is not a bundled operator UI, payment processor, tax engine, or general-purpose accounting system, and a direct payment-provider integration is usually simpler when only fixed recurring subscriptions are needed. Releases are beta and can include breaking changes, so operators must review releases and migration guides when upgrading.

git clone https://github.com/openmeterio/openmeter.git
cd openmeter/quickstart
docker compose up -d --wait

curl -sS -o /dev/null -w '%{http_code}\n' \
  -X POST http://localhost:48888/api/v1/events \
  -H 'Content-Type: application/cloudevents+json' \
  --data-raw '{
    "specversion": "1.0",
    "type": "request",
    "id": "readme-curl-1",
    "source": "readme",
    "subject": "readme-curl",
    "data": { "method": "GET", "route": "/hello" }
  }'

response=
for attempt in 1 2 3 4 5 6 7 8 9 10; do
  response=$(curl -fsS 'http://localhost:48888/api/v1/meters/api_requests_total/query?subject=readme-curl')
  printf '%s' "$response" | grep -q '"value":1' && break
  sleep 1
done
printf '%s\n' "$response"

npm install @openmeter/sdk tsx

import { OpenMeter } from '@openmeter/sdk'

const openmeter = new OpenMeter({ baseUrl: 'http://localhost:48888' })

const queryUsage = () =>
  openmeter.meters.query('api_requests_total', {
    subject: ['readme-typescript'],
  })

async function main() {
  await openmeter.events.ingest({
    type: 'request',
    id: 'readme-typescript-1',
    source: 'readme',
    subject: 'readme-typescript',
    data: { method: 'GET', route: '/hello' },
  })

  let usage = await queryUsage()
  for (let attempt = 1; usage.data[0]?.value !== 1 && attempt < 10; attempt++) {
    await new Promise((resolve) => setTimeout(resolve, 1000))
    usage = await queryUsage()
  }

  if (usage.data[0]?.value !== 1) {
    throw new Error('usage was not processed in time')
  }
  console.log(usage.data[0].value)
}

main().catch((error) => {
  console.error(error)
  process.exitCode = 1
})

python -m pip install --pre openmeter

import time

from openmeter import Client
from openmeter.models import Event

with Client(endpoint="http://localhost:48888") as openmeter:
    openmeter.events.ingest_event(
        Event(
            id="readme-python-1",
            source="readme",
            specversion="1.0",
            type="request",
            subject="readme-python",
            data={"method": "GET", "route": "/hello"},
        )
    )

    for _ in range(10):
        usage = openmeter.meters.query_json(
            "api_requests_total",
            subject=["readme-python"],
        )
        if usage.data and usage.data[0].value == 1:
            break
        time.sleep(1)
    else:
        raise RuntimeError("usage was not processed in time")

    print(usage.data[0].value)

docker compose down -v