Implementing Per‑Tenant Billing, Quota Enforcement, and Usage Analytics for the OpenClaw Rating API

1. Introduction

Multi‑tenant SaaS products must isolate each customer’s usage, charge them accurately, and provide visibility into consumption. The OpenClaw Rating API—a powerful tool for rating and scoring data—fits perfectly into this model, but it requires a custom billing layer, quota enforcement, and analytics dashboard. This guide walks UBOS developers, DevOps engineers, and SaaS product managers through a complete implementation, from data modeling to production‑ready testing.

By the end of this article you will have a working prototype that you can extend, scale, and integrate with UBOS’s UBOS partner program for additional support.

2. Overview of OpenClaw Rating API

The OpenClaw Rating API evaluates incoming data against a set of configurable rules and returns a numeric score. It is stateless, REST‑ful, and can be self‑hosted. For a deep dive into the official documentation, see the OpenClaw GitHub repository.

• Supports JSON payloads up to 5 MB.
• Returns a { score: number, details: object } response.
• Can be extended with custom rule plugins.

When hosted on UBOS, the API can leverage the Web app editor on UBOS for rapid iteration and the Workflow automation studio for CI/CD pipelines.

3. Architecture for per‑tenant billing

Data model

A clean, MECE‑compliant schema isolates tenant data while keeping billing logic simple. Below is a minimal PostgreSQL model:

CREATE TABLE tenants (
    tenant_id   UUID PRIMARY KEY,
    name        TEXT NOT NULL,
    api_key     TEXT UNIQUE NOT NULL,
    created_at  TIMESTAMP DEFAULT NOW()
);

CREATE TABLE usage_records (
    id          SERIAL PRIMARY KEY,
    tenant_id   UUID REFERENCES tenants(tenant_id),
    endpoint    TEXT NOT NULL,
    request_ts  TIMESTAMP DEFAULT NOW(),
    bytes_sent  INTEGER,
    cost_cents  INTEGER
);
    

Billing service design

The billing service runs as a separate microservice that subscribes to usage events (via a message queue such as RabbitMQ or UBOS’s native event bus). It aggregates usage per billing cycle and writes invoices to the billing_invoices table.

# billing_service.py
import os, json
from ubos.event import subscribe

COST_PER_KB = 0.02  # cents

def handle_usage(event):
    tenant = event["tenant_id"]
    bytes_sent = event["bytes_sent"]
    cost = int(bytes_sent / 1024) * COST_PER_KB
    # Persist cost
    # (pseudo‑code, replace with ORM call)
    db.insert("usage_records", {
        "tenant_id": tenant,
        "endpoint": event["endpoint"],
        "bytes_sent": bytes_sent,
        "cost_cents": cost
    })

subscribe("openclaw.usage", handle_usage)
    

For pricing flexibility, consult the UBOS pricing plans and map them to your own tier definitions.

4. Implementing quota enforcement

Middleware approach

The most maintainable way to enforce quotas is through API gateway middleware. UBOS’s Enterprise AI platform by UBOS includes a built‑in gateway that can execute custom scripts before forwarding the request.

// quota-middleware.js (Node.js Express example)
module.exports = async function(req, res, next) {
  const apiKey = req.headers['x-api-key'];
  const tenant = await db.query('SELECT * FROM tenants WHERE api_key=$1', [apiKey]);
  if (!tenant) return res.status(401).json({error: 'Invalid API key'});

  const usage = await db.query(
    `SELECT SUM(bytes_sent) AS total FROM usage_records
     WHERE tenant_id=$1 AND request_ts > now() - interval '1 month'`,
    [tenant.rows[0].tenant_id]
  );

  const monthlyQuota = 10 * 1024 * 1024; // 10 MB per month
  if (usage.rows[0].total + req.headers['content-length'] > monthlyQuota) {
    return res.status(429).json({error: 'Quota exceeded'});
  }

  // Attach tenant info for downstream services
  req.tenant = tenant.rows[0];
  next();
};
    

Example code snippets

For Python‑based services, the same logic can be expressed as a FastAPI dependency:

# quota_dependency.py
from fastapi import Header, HTTPException, Depends
from sqlalchemy import select, func
from models import Tenant, UsageRecord, db

async def verify_quota(x_api_key: str = Header(...)):
    tenant = await db.scalar(select(Tenant).where(Tenant.api_key == x_api_key))
    if not tenant:
        raise HTTPException(status_code=401, detail="Invalid API key")

    total = await db.scalar(
        select(func.sum(UsageRecord.bytes_sent))
        .where(UsageRecord.tenant_id == tenant.id)
        .where(UsageRecord.request_ts > func.now() - text("interval '1 month'"))
    ) or 0

    if total + 1024 > 10 * 1024 * 1024:  # assume 1 KB request
        raise HTTPException(status_code=429, detail="Quota exceeded")
    return tenant
    

5. Capturing usage analytics

Event logging

Every request that passes the quota middleware should emit an openclaw.usage event. UBOS’s event bus guarantees at‑least‑once delivery, enabling reliable analytics pipelines.

// after‑rating.js (called after OpenClaw returns a score)
const { publish } = require('ubos-event-bus');

function logUsage(req, response) {
  publish('openclaw.usage', {
    tenant_id: req.tenant.id,
    endpoint: req.path,
    bytes_sent: Buffer.byteLength(JSON.stringify(req.body)),
    response_time_ms: response.time,
    score: response.body.score
  });
}
    

Reporting dashboard

UBOS ships with a low‑code dashboard builder. Use the AI marketing agents to auto‑generate visualizations of:

• Monthly spend per tenant.
• Average score distribution.
• Quota breach trends.

For a ready‑made template, import the AI SEO Analyzer and replace the data source with your usage events.

6. Step‑by‑step implementation guide

Prerequisites

• UBOS account with access to the UBOS homepage.
• Docker Engine ≥ 20.10 and Git.
• Node.js 18+ or Python 3.10+ (choose one language for the examples).

Code setup (repository clone, dependencies)

Clone the starter repo that contains a minimal OpenClaw wrapper and the billing microservice:

git clone https://github.com/ubos-tech/openclaw-billing-starter.git
cd openclaw-billing-starter
# Node example
npm install
# Python example
pip install -r requirements.txt
    

Detailed code examples (Node.js/Python)

Node.js – API gateway with quota middleware

const express = require('express');
const quota = require('./quota-middleware');
const { rateOpenClaw } = require('./openclaw-client');

const app = express();
app.use(express.json());
app.use(quota);

app.post('/rate', async (req, res) => {
  const result = await rateOpenClaw(req.body);
  // Emit usage event
  const { publish } = require('ubos-event-bus');
  publish('openclaw.usage', {
    tenant_id: req.tenant.id,
    endpoint: '/rate',
    bytes_sent: Buffer.byteLength(JSON.stringify(req.body)),
    score: result.score
  });
  res.json(result);
});

app.listen(8080, () => console.log('OpenClaw gateway listening on :8080'));
    

Python – FastAPI service with dependency injection

from fastapi import FastAPI, Depends
from quota_dependency import verify_quota
from openclaw_client import rate_payload
from ubos.event import publish

app = FastAPI()

@app.post("/rate")
async def rate(data: dict, tenant = Depends(verify_quota)):
    result = await rate_payload(data)
    await publish("openclaw.usage", {
        "tenant_id": tenant.id,
        "endpoint": "/rate",
        "bytes_sent": len(str(data).encode()),
        "score": result["score"]
    })
    return result
    

Testing the implementation

Use curl or httpie with a valid API key. The following script checks quota enforcement and billing record creation:

API_KEY="your-tenant-api-key"
for i in {1..12}; do
  curl -X POST http://localhost:8080/rate \
    -H "Content-Type: application/json" \
    -H "X-API-Key: $API_KEY" \
    -d '{"text":"sample payload"}' -w "\n"
done
# Verify usage records
psql -d ubos -c "SELECT * FROM usage_records WHERE tenant_id='$(uuidgen)';"
    

7. Best‑practice tips

• Secure API keys. Rotate keys regularly and store them in UBOS’s secret manager. See the About UBOS page for security best practices.
• Monitoring and alerts. Hook usage events into UBOS’s alerting engine to receive Slack or email notifications when a tenant approaches 80 % of its quota.
• Scaling considerations. Deploy the billing service as a stateless container behind a load balancer. Leverage the UBOS solutions for SMBs scaling guide for auto‑scaling policies.
• Data retention. Archive usage records older than 12 months to a cold storage bucket to keep the primary DB lean.
• Testing in CI. Include integration tests that simulate quota breaches and verify invoice generation.

8. Conclusion

By following the architecture and step‑by‑step guide above, you can deliver a production‑grade OpenClaw Rating API that respects per‑tenant billing, enforces usage quotas, and provides actionable analytics—all within the UBOS templates for quick start. This foundation empowers your SaaS business to scale responsibly while keeping customers informed about their consumption.

Ready to see the solution in action? Host OpenClaw on UBOS today and start monetizing your AI‑driven rating engine.