Pay As You Go

Welcome to the ZenMux Pay As You Go plan! This guide will help you understand the key benefits of Pay As You Go, and how to top up, manage your balance, and create production-grade API keys.

💡 Best for production

Pay As You Go is a usage-based billing plan built specifically for production. It offers no rate limits, no concurrency limits, production-grade stability, and transparent, precise billing.

What is Pay As You Go?

Pay As You Go is ZenMux’s billing plan tailored for enterprise customers and production use. Unlike subscription plans, Pay As You Go uses a prepaid balance + pay-as-you-consume model, so you only pay for the API usage you actually consume.

Key features

Feature	Description
No Rate Limit	No per-minute request limit; supports high-concurrency workloads
Production-grade stability	SLA coverage plus an AI insurance compensation mechanism
Precise billing	Token-level billing for transparent and controllable costs
Enterprise services	Full request logs, cost analytics, and billing statistics

Why choose Pay As You Go?

Use cases

Pay As You Go is especially suitable for:

Commercial AI products already in production — no concurrency limits, stable and reliable
AI services for end users — production-grade stability guarantees
AI agent business systems — precise billing based on actual consumption
Enterprise application integrations — predictable costs and auditable billing

Differences vs. subscriptions

Dimension	Pay As You Go	Builder Plan (Subscription)
Best for	Production, commercial products	Personal development, learning & experimentation
Rate Limit	✅ Unlimited	⚠️ 10–15 RPM
Concurrency	✅ Unlimited	⚠️ Weekly Limit applies
Stability	✅ Production-grade	Standard
Cost model	Precise usage-based billing	Fixed monthly fee
Usage restrictions	No special restrictions	❌ Not allowed for production use

⚠️ Important

If your project is already live or about to be commercialized, you must use Pay As You Go. The subscription plan (Builder Plan) is only for personal development and learning scenarios (Vibe Coding and Media Create scenarios) and must not be used in production. Violations may impact your account.

How to use Pay As You Go

Go to the ZenMux Console and navigate to Manage > Pay As You Go.

Pay As You Go page

Step 2: Check your balance

At the top of the page, you’ll see three balance types:

Total Balance: your current total available credits
Top-Up Credits: credits obtained from top-ups
Bonus & Compensation Credits: credits from top-up bonuses, referral rewards, insurance compensation, etc.

💡 Balance notes

All credits are denominated in USD ($). 1 credit equals $1 worth of API usage. During consumption, bonus credits are used first, then top-up credits.

Step 3: Top up your account

Manual top-up

Click the Top Up button in the top-right corner
Choose a top-up amount (custom amounts supported)
Complete payment (Stripe, Alipay, and more supported)
After a successful top-up, credits are applied immediately and you’ll automatically receive an additional 20% bonus credits

Top-up bonus examples:

Top-up amount	Credits received	Bonus rate
$100	$120	+20%
$500	$600	+20%
$1000	$1200	+20%

Auto Top-Up

To avoid service impact from insufficient balance, you can enable Auto Top-Up:

Click Auto Top-Up
Set the trigger threshold (e.g., trigger when balance falls below $10)
Set the top-up amount per charge (e.g., $100 each time)
Link a payment method and save

Once enabled, the system will automatically top up when your balance falls below the configured threshold—ensuring your API service won’t be interrupted due to low balance.

Create and manage API keys

Create a Pay As You Go API key

Pay As You Go API keys are completely separate from subscription keys and are designed for production:

In Pay As You Go API Keys, click + Create API Key
Enter a name for the API key (e.g., production-app)
Click Create to finish

Create API key

API key management

In the API Keys list, you can view and manage all Pay As You Go API keys:

Column	Description
Name	API key name
API Key	API key prefix (click to copy the full key)
Status	Status (Enabled/Disabled)
Created	Created date
Last Used	Last used time
Used	Amount consumed
Activity	Actions (view details, edit, delete)

💡 API key best practices

Create separate API keys for different projects/environments to simplify cost attribution and management
Regularly review Last Used and Used to identify inactive or high-spend keys
If you suspect a key has been leaked, immediately disable or delete it via the Actions column

Call the API with a Pay As You Go API key

After creating an API key, you can use it in code to call the ZenMux API. The usage is exactly the same as in the quickstart guide—just replace it with your Pay As You Go API key:

PythonTypeScript

python

from openai import OpenAI

client = OpenAI(
    base_url="https://zenmux.ai/api/v1",
    api_key="<YOUR PAY_AS_YOU_GO_API_KEY>",  
)

completion = client.chat.completions.create(
    model="openai/gpt-5",
    messages=[
        {
            "role": "user",
            "content": "What is the meaning of life?"
        }
    ]
)

print(completion.choices[0].message.content)

import OpenAI from "openai";

const openai = new OpenAI({
  baseURL: "https://zenmux.ai/api/v1",
  apiKey: "<YOUR PAY_AS_YOU_GO_API_KEY>",  
});

async function main() {
  const completion = await openai.chat.completions.create({
    model: "openai/gpt-5",
    messages: [
      {
        role: "user",
        content: "What is the meaning of life?",
      },
    ],
  });

  console.log(completion.choices[0].message);
}

main();

📚 More usage

For complete API usage examples, see the Quickstart Guide.

Balance management and billing

View balance breakdown

Click the info icon next to Total Balance to view the Credits Breakdown:

Credits breakdown

The breakdown includes:

Top-ups: your top-up records
Bonuses: the 20% bonus credits from top-ups
Gifts: credits granted by the platform
Referrals: rewards earned from referring friends
Compensations: AI insurance compensation credits
Adjustments: manual credit adjustments by the platform
Expired: expired bonus credits
Usage: credits consumed by API calls
Total Balance: current total available credits

View transaction history

In Transaction History, you can review all top-ups, usage, and compensation records:

Column	Description
Date	Transaction date and time
Amount	Transaction amount
Type / Method	Transaction type (Insurance compensation, Stripe top-up, Discount, etc.)
Description / Invoice	Transaction description or invoice link

Click View Invoice to download the corresponding top-up invoice for reimbursements and billing audits.

FAQ

How can I avoid service interruptions due to insufficient balance?

Enable Auto Top-Up. With a reasonable trigger threshold and top-up amount configured, the system will automatically top up when your balance is low, ensuring uninterrupted service.

Can I use Pay As You Go and a subscription plan at the same time?

Yes. You can use the Builder Plan (Subscription) during personal development, and switch to Pay As You Go when going live or commercializing. API keys for the two plans are completely independent.

How long does it take for credits to arrive after topping up?

Credits are applied immediately after a successful top-up—no waiting required. The system also automatically adds a 20% bonus.

How do I view usage details for a specific API key?

In the Pay As You Go API Keys list, click Details for the corresponding key to view detailed usage records and request logs.

How do I export invoices for company reimbursement?

In Transaction History, click View Invoice for the relevant top-up record to download an official top-up invoice (PDF), suitable for reimbursement and financial audits.

Next steps

Now that you understand how Pay As You Go works, you can:

Read the Advanced Calling Guide to learn streaming, multimodal, and other advanced features
Review the AI Insurance Docs to learn how to file claims
Visit the Cost Analytics page for detailed cost attribution and usage trends
Join the Discord community to connect with other developers

If you run into any issues or have suggestions/feedback, feel free to reach us via:

Website: https://zenmux.ai
Support email: [email protected]
Business email: [email protected]
Twitter: @ZenMuxAI
Discord: http://discord.gg/vHZZzj84Bm

For more contact options and details, visit our Contact page.

Pay As You Go ​

What is Pay As You Go? ​

Key features ​

Why choose Pay As You Go? ​

Use cases ​

Differences vs. subscriptions ​

How to use Pay As You Go ​

Step 1: Sign in to the console ​

Step 2: Check your balance ​

Step 3: Top up your account ​

Manual top-up ​

Auto Top-Up ​

Create and manage API keys ​

Create a Pay As You Go API key ​

API key management ​

Call the API with a Pay As You Go API key ​

Balance management and billing ​

View balance breakdown ​

View transaction history ​

FAQ ​

How can I avoid service interruptions due to insufficient balance? ​

Can I use Pay As You Go and a subscription plan at the same time? ​

How long does it take for credits to arrive after topping up? ​

How do I view usage details for a specific API key? ​

How do I export invoices for company reimbursement? ​

Next steps ​