# Service tiers
URL: https://docs.munito.ai/service-tiers

Each request runs in one of three service tiers. The tier sets the order in which a model serves requests and the price.

| Tier       | Price   | When the model is busy                       | Use it for                         |
| ---------- | ------- | -------------------------------------------- | ---------------------------------- |
| `priority` | Highest | Served first. A `503` is the least likely.   | Traffic that a user waits for      |
| `standard` | Middle  | Served after priority. This is the default.  | Most traffic                       |
| `flex`     | Lowest  | Served last, and refused first with a `503`. | Evaluations, batch jobs, backfills |

The model, its output and zero data retention are the same in each tier. When the model has free capacity, all three tiers run at the same speed.

## Choose a tier [#choose-a-tier]

Send the `munito-service-tier` header with `priority`, `standard` or `flex`:

```bash
curl https://api.munito.ai/inference/v1/chat/completions \
  -H "Authorization: Bearer $MUNITO_API_KEY" \
  -H "munito-service-tier: flex" \
  -H "Content-Type: application/json" \
  -d '{"model": "qwen/qwen3.8-27b", "messages": [{"role": "user", "content": "Hello"}]}'
```

Chat Completions and Responses also accept the OpenAI `service_tier` field: `priority`, `flex`, or `default` for standard. When a request sends both, the header wins. Messages reads only the header.

The `munito-service-tier` response header names the tier that is billed. A chat completion also names it in the `service_tier` field, with `default` for standard.

## Limits of each tier [#limits-of-each-tier]

- **Priority** needs a paid account. On the free tier, a priority request gets `403`.
- **Flex** gets a `503` sooner than the other tiers, and [overflow](https://docs.munito.ai/overflow) does not apply to it. Send flex work as a background request, so that it waits in line for capacity: `Prefer: respond-async` on Chat Completions, or `background: true` on Responses.
- A request above your [rate limit](https://docs.munito.ai/rate-limits) can still run on spare capacity. The response then carries `x-ratelimit-over-limit: yes`, and you pay the price of the tier that you asked for.