# Rate limits

> Provider rate limits are retried for you and surface on the task, not as an HTTP error. A key's spending limit is a 402, not a 429.

Mynth is built for production traffic, and a normal app should not need a
backoff loop. There are two kinds of limit to plan for, and they show up in
different places.

## Limits on your requests

Capacity limits can apply to protect the service. Do not build code that
assumes a key can send without limit. If you get a `429`, slow down and retry
with backoff. There is no `Retry-After` header. The CLI exits with code `6`
for a `429`.

A key's [spending limit](https://mynth.io/docs/authentication.md#spending-limits) is not a rate
limit. It answers `402 SPENDING_LIMIT_EXCEEDED`, and a retry does not clear
it. The key's day, week, or month has to roll over, or you raise the cap.

## Limits at the provider

Providers rate-limit Mynth. A refused attempt is retried on another provider,
within the attempt budget on [tasks](https://mynth.io/docs/concepts/tasks.md#retries-and-timeouts),
and you do not see those retries.

When every attempt is refused, the item fails on a task that was already
accepted:

| Code             | Means                                             | Do                                 |
| ---------------- | ------------------------------------------------- | ---------------------------------- |
| `RATE_LIMITED`   | Providers kept rate-limiting the request          | Send a new request shortly         |
| `PROVIDERS_BUSY` | No provider has capacity for this model right now | Retry later, or pick another model |

Neither is an HTTP `429` on the create call. The code sits on the failed
image or video inside a `completed` task, and failed items are not charged.
[Errors](https://mynth.io/docs/api-reference/errors.md#task-failures) lists every task code.

## Next steps

- [Authentication](https://mynth.io/docs/authentication.md#spending-limits): set a spending limit on a key.
- [Tasks](https://mynth.io/docs/concepts/tasks.md#retries-and-timeouts): attempts and time budgets.
- [Errors](https://mynth.io/docs/api-reference/errors.md): every HTTP status and task code.