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Karta billing is prepaid. Model usage draws down a credit balance you top up in advance, so there are no metered invoices and no bill shock: an org can never owe Karta more than it has already paid. When the balance runs out, requests pause with 402 Payment Required until you top up.

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Plans

Current plan names, prices, and included credits are shown in the console when you choose a plan. They are left off this page so it cannot drift out of sync with live pricing.
Karta has a free tier to start with no card and no key, paid plans for ongoing use, and a custom Enterprise plan. Managed plans run on Karta’s platform model key and prepaid credits; bringing your own provider key (BYOK) is a paid-plan capability - see BYOK.

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Credits

Credits are face dollars. Buy them in packs from the billing page; pack prices include payment processing, so receipts show one number. Usage draws the balance down at the model’s token cost plus Karta’s platform fee - the current pack sizes, fee, and any included monthly credit are shown in the console.
  • Auto-refill (optional) - buy a chosen pack automatically when the balance drops below a threshold you set. A monthly cap is required when enabling it: it bounds the worst case for a runaway agent at your cap plus one pack. Failures never block buying manually.
  • Out of credits - requests return 402 with reason credits_exhausted. Agents resume the moment the balance is positive again.

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Rate card

Model usage is priced per token, tracking the model vendors’ published API pricing; the current per-model rates are shown in the console. On managed plans, the credit drawdown is the token cost plus Karta’s platform fee. On BYOK, you pay your provider directly for tokens and Karta charges only the platform fee.

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The prepaid guarantee

  • No code path can bill you past your collected balance. Usage can briefly overshoot by the in-flight turn (agents finish their current response); the overshoot is absorbed by Karta, never invoiced.
  • Refunds and chargebacks are deducted from the credit balance; if it goes negative, usage pauses until a top-up - never a bill.
  • The plan subscription fee is the only recurring charge, and it is flat.

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Recovery checklist