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Getting started

Every new account starts with $10 of free credit to evaluate the models. To create API keys you first add a billing address and a credit card from the dashboard — see Adding a card. You’re billed per token at per-model rates, drawing down your free credit first; once it’s used, top up to keep requests flowing.

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How we bill

Dollar-denominated, per-request. We don’t sell token bundles, we don’t subscribe you — we meter what you use: Per-model pricing is in the catalog. Spend appears in the dashboard within a few minutes of each request.
Streaming a chat completion and stopping early still bills for the tokens that were generated before you closed the connection — the model did the work. Set max_tokens to cap worst-case spend.

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Rate limits

Per-API-key, per-minute. Limits are set by tier: The tier is stored on the key. If you need more than the free tier, request an upgrade from the dashboard or email support@flex.ai. Every response from the API carries rate-limit headers: When you exceed the limit you get 429 Too Many Requests with a Retry-After header (seconds to wait). Don’t retry in a tight loop — back off until the header’s deadline.

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When credit runs out

Our API returns 402 Payment Required with this body:
Once you add credit, subsequent requests succeed immediately — no key regeneration needed.

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Adding a card

From dashboard/billing:
  1. Click Add payment method.
  2. Enter card details (processed by Stripe; we never see the number).
  3. Top up by any amount ≥ $5. The balance is added to your account immediately.
There’s no auto-recharge at launch — you’ll get an email when your balance drops below 5andagainwhenithits5 and again when it hits 0.