> ## Documentation Index
> Fetch the complete documentation index at: https://apione.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Find and choose models

> Check available model IDs, capabilities, and parameters for your key.

First list the models available to your key, then check capabilities and prices. A display name or vendor name is not necessarily the request's model ID.

![Compare available models, capabilities, prices, and channels in APIONE.](https://mintcdn.com/apione/pAFvFGkbmcRZirTZ/images/ui/model-catalog.png?fit=max\&auto=format\&n=pAFvFGkbmcRZirTZ\&q=85\&s=b60b5a7f06c1e256c10ccd1d1e19f9f0)

Compare available models, capabilities, prices, and channels in APIONE.

## List available models

Set `APIONE_API_KEY`, then query:

```bash theme={null}
curl --fail-with-body https://api.apione.ai/v1/models \
  -H "Authorization: Bearer $APIONE_API_KEY"
```

Copy IDs from `data[].id`, preserving case. APIONE does not require provider prefixes used by other gateways.

The public directory can contain models that are unavailable to the current key. An example does not guarantee permanent availability. Recheck access after changing keys, billing groups, or model versions.

## Query parameters

`GET /v1/models/{model}/params` returns model parameter and billing information. URL-encode the model ID when placing it in the path.

| Field | Type | What to check |
| - | - | - |
| `model` | string | The model ID queried |
| `params` | string\[] | Extra parameters declared by the model |
| `request` | object | Request fields and allowed values |
| `billingMode` | string | Read the mode actually returned; an empty string is undeclared and does not establish the charge |
| `chargeModes` | string\[] | Allowed charge modes: `usage`, `request`, `second`, and `image` |

Use the actual response; a parameter name alone does not establish other capabilities. A missing or inaccessible model may return 404. Verify the ID and access with the model list first.

The [model directory](https://apione.ai/en/models) provides prices, context information, and input types. See [group pricing and billing](https://apione.ai/docs/en/account/usage.md) for how groups affect charges.

![Search the APIONE model directory and review matching models.](https://mintcdn.com/apione/pAFvFGkbmcRZirTZ/images/ui/model-search.png?fit=max\&auto=format\&n=pAFvFGkbmcRZirTZ\&q=85\&s=633884d33b4d84dea7581b434b5b5a50)

Search the APIONE model directory and review matching models.

![Review a model's context, output limits, capabilities, and prices.](https://mintcdn.com/apione/pAFvFGkbmcRZirTZ/images/ui/model-detail.png?fit=max\&auto=format\&n=pAFvFGkbmcRZirTZ\&q=85\&s=35c168af320d711f179c4acd0bfee9f2)

Review a model's context, output limits, capabilities, and prices.

## Selection process

1. Identify the task, input/output types, and protocol.
2. Check context, maximum output, structured output, tools, and other required capabilities.
3. Compare quality, latency, and usage on the same representative, redacted samples.
4. Store the model ID in configuration or an environment variable. Verify with limited traffic before production rollout.

## Capability checks

| Common distinction | Check separately |
| - | - |
| Image input and image generation | Image understanding does not establish image generation support |
| Chat Completions and Responses | A model may support the endpoints differently |
| Structured output | Verify JSON object and JSON Schema support separately |
| Tool calling | Your application executes requested functions and returns their results |

Do not reuse other gateways' special model suffixes or routing names. APIONE selects from the model's available channels; requests cannot select a channel or region. See the [routing reference](https://apione.ai/en/api-docs/docs/smart-routing).

## When parameter metadata is empty

HTTP 200 with `params: []`, `request: {}`, or an empty `billingMode` means those details were not declared in this response. It does not prove that a capability is unsupported, permit arbitrary parameters, or indicate a free call. The `usage`, `request`, `second`, and `image` entries in `chargeModes` are listed mode names, not proof that a model bills all four ways.

1. Check the APIONE model details and current key group for protocols and prices.
2. Use confirmed model-specific instructions for size, quality, reference images, masks, and other fields; do not copy enums from another model.
3. Without confirmed parameter instructions, verify the minimal request first and avoid optional fields or batch jobs.
4. Contact support with the model ID, endpoint, time, and actual request identifiers. Do not send the full key.

Continue with [chat parameters](https://apione.ai/docs/en/models/chat.md) and [structured output and tools](https://apione.ai/docs/en/models/advanced.md). See the [public model reference](https://apione.ai/en/api-docs/docs/model-list) for interface details.


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