> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mythic-c2.net/llms.txt
> Use this file to discover all available pages before exploring further.

# JSONString Parameters

> Render guided JSON forms for payload build and C2 profile parameters

Mythic 4.0 adds the `JSONString` parameter type for payload build parameters and C2 profile parameters. The stored value remains a JSON **string**, while `json_string_schema` lets the Create Payload UI offer synchronized **Visual** and **Source** editors.

<Info>
  The schema is declarative UI metadata, not JSON Schema draft-07/2020-12. Use the supported vocabulary below.
</Info>

## Python example

```python theme={"system"}
from mythic_container.PayloadBuilder import BuildParameter, BuildParameterType

http_config_schema = {
    "type": "object",
    "label": "HTTP Configuration",
    "fields": [
        {"name": "callback_host", "type": "string", "label": "Callback Host"},
        {"name": "callback_port", "type": "number", "label": "Port"},
        {"name": "use_ssl", "type": "boolean", "label": "Use TLS"},
        {
            "name": "method",
            "type": "enum",
            "label": "HTTP Method",
            "choices": ["GET", "POST"],
            "choices_display_names": {"GET": "HTTP GET", "POST": "HTTP POST"},
        },
        {
            "name": "headers",
            "type": "string_map",
            "label": "Headers",
            "key_label": "Header",
            "value_label": "Value",
        },
        {
            "name": "client_certificate",
            "type": "string",
            "label": "Client certificate",
            "show_when": {"field": "use_ssl", "in": [True]},
        },
    ],
}

build_parameters = [
    BuildParameter(
        name="http_config",
        display_name="HTTP Configuration",
        parameter_type=BuildParameterType.JSONString,
        default_value='{"callback_host":"https://example.com","callback_port":443,"use_ssl":true,"method":"POST","headers":{}}',
        json_string_schema=http_config_schema,
    )
]
```

The same schema can be supplied to `C2ProfileParameter(..., parameter_type=ParameterType.JSONString, json_string_schema=http_config_schema)`.

## Go example

```go theme={"system"}
configSchema := map[string]interface{}{
    "type":  "object",
    "label": "HTTP Configuration",
    "fields": []map[string]interface{}{
        {"name": "callback_host", "type": "string", "label": "Callback Host"},
        {"name": "callback_port", "type": "number", "label": "Port"},
        {"name": "use_ssl", "type": "boolean", "label": "Use TLS"},
        {
            "name": "headers",
            "type": "string_map",
            "label": "Headers",
            "key_label": "Header",
            "value_label": "Value",
        },
    },
}

parameter := agentstructs.BuildParameter{
    Name:             "http_config",
    DisplayName:      "HTTP Configuration",
    ParameterType:    agentstructs.BUILD_PARAMETER_TYPE_JSON_STRING,
    DefaultValue:     `{"callback_host":"https://example.com","callback_port":443,"use_ssl":true,"headers":{}}`,
    JsonStringSchema: configSchema,
}
```

For a C2 profile, use `c2structs.C2_PARAMETER_TYPE_JSON_STRING` and the `JsonStringSchema` field.

## Schema vocabulary

| `type`       | Stored JSON value            | Important fields                               |
| ------------ | ---------------------------- | ---------------------------------------------- |
| `object`     | object                       | `fields`, where each field has a unique `name` |
| `array`      | array                        | `items` schema                                 |
| `enum`       | one primitive value          | `choices`, optional `choices_display_names`    |
| `string`     | string                       | optional `placeholder`                         |
| `number`     | number                       | —                                              |
| `boolean`    | boolean                      | —                                              |
| `string_map` | object of string keys/values | optional `key_label`, `value_label`            |

All nodes can include `label` and `description`. A field inside an object's `fields` can include:

* `show_when: {field: "sibling_name", in: [values...]}` to control visibility;
* `placeholder_when: {field: "sibling_name", map: {value: "placeholder"}}` for a contextual string placeholder.

Hidden fields keep their current value. Consumers should tolerate a value that is present even when its editor control is hidden.

## Round-trip behavior

The Source editor holds the exact string. Switching to Visual calls `JSON.parse`; invalid JSON blocks the switch. Each visual change is serialized back with formatted JSON. The top-level schema should therefore describe the JSON document itself, normally an `object`.

The UI seeds missing values as `{}` for objects and maps, `[]` for arrays, `""` for strings, `0` for numbers, `false` for booleans, and the first enum choice when available.