Prepaid vs Postpaid AI Billing: Why Wallets Beat Monthly Invoices

The postpaid default, and why it's risky for AI specifically

Most software billing is postpaid: use the service, get invoiced at the end of the cycle. This works fine when usage is predictable — seats, storage, fixed subscriptions.

LLM usage is not predictable in the same way. A single prompt can vary in cost by 10x depending on input length, an agent loop can call the same endpoint hundreds of times in minutes, and a bug in a retry handler can turn a normal day into a runaway bill. Postpaid billing means you find out about all of this after it happened, on an invoice, once it's too late to stop it.

How a prepaid wallet changes the risk

With a prepaid wallet, you decide the ceiling before any usage happens: top up ₹500, and the maximum possible spend for that period is ₹500. There is no invoice at the end of the month with a number you didn't expect, because there is no credit extended — only balance being drawn down in real time.

| | Postpaid (direct provider billing) | Prepaid wallet | |---|---|---| | When you learn the cost | End of billing cycle, after usage | Continuously, as balance depletes | | Maximum possible spend | Unbounded unless you set external limits | Capped at wallet balance | | Runaway bug protection | None built in — relies on you noticing | Requests stop when balance hits zero | | Per-key spend control | Rare, often account-wide only | Per-key budget caps available | | Payment method | Card on file, charged automatically | You choose when and how much to add |

Per-key budgets: prepaid logic one level down

AICredits wallets go a level further than "stop at zero" — each individual API key can carry its own budget cap. A team can run five keys off one account-level wallet: engineering gets ₹2,000, the data team gets ₹1,500, and a sandbox/testing key gets ₹500, all from the same pool but independently capped. If the sandbox key's budget is misused by an experimental script, it stops there — it can't touch the other four keys' allocations.

Account wallet: ₹5,000
  ├─ key: engineering    (budget cap ₹2,000)
  ├─ key: data-team      (budget cap ₹1,500)
  └─ key: sandbox        (budget cap ₹500)

This is the practical version of "set a spending limit" that most providers don't offer at the API key level — you get it as a first-class feature of a prepaid model, not a workaround.

What this means for finance and budgeting

A prepaid wallet also simplifies internal accounting. Instead of reconciling a variable USD invoice against a budgeted INR number every month, a top-up is a single, known outflow — ₹5,000 added to the wallet is ₹5,000 spent, full stop, whenever it happens. There's no month-end surprise to explain.

Frequently Asked Questions

What happens when the wallet balance hits zero?

New requests are rejected until you top up. In-flight requests already accepted are not interrupted, but no new ones are accepted below the balance threshold.

Can I set up automatic top-ups so requests never fail?

Manual top-up via UPI, net banking, or debit card is the default flow. If predictable recurring spend matters more than hard caps for your use case, plan top-ups on a regular cadence rather than relying on auto-recharge.

Do unused credits expire?

Credits are valid for one year from the date they're added, using FIFO deduction — the oldest credits in your wallet are used first.

Is a prepaid model slower to start using than postpaid?

No — signup takes minutes and the minimum top-up is ₹10. You're testing models within the same session you create an account, not waiting on a billing approval process.

Get started

• Create a free account and top up ₹10 via UPI to see the wallet model in action.
• Set up per-key budget caps for your team's API keys.
• Related: How to Estimate Your LLM API Costs Before You Ship.