# Suggest subject lines with AI

> Scale plan. Five subject line and preview text pairs with different angles for a builder document.

Source: https://docs.pidgely.com/api-reference/template-builder/ai-subjects/

`POST https://api.pidgely.com/template-builder/ai/subjects`

Scale plan. Five subject line and preview text pairs with different angles for a builder document.

Five suggestions with different angles. Scale plan.

**Authorization:** `Bearer pdg_…`. An API key with `full_access`. A `sending_access` key gets `401 restricted_api_key`.

## Body parameters

JSON object.

| Name | Type | Required | Description |
|---|---|---|---|
| `document` | object | Yes | Visual builder document (Pidgely extension, Scale plan). The server renders it to table-based e-mail HTML with Outlook (VML) buttons, responsive and dark-mode rules, and a plain-text version. |
| `document.version` | integer | No | One of `1`. |
| `document.preview_text` | string | No | Preview text shown by mail clients next to the subject (inserted as hidden text at the top of the HTML). |
| `document.theme` | object | No | Global look of a builder e-mail. Colors are hex (`#rrggbb`). |
| `document.theme.brand_color` | string | No | — |
| `document.theme.text_color` | string | No | — |
| `document.theme.background_color` | string | No | — |
| `document.theme.content_color` | string | No | Background of the content card. |
| `document.theme.link_color` | string | No | — |
| `document.theme.font` | string | No | One of `system`, `inter`, `helvetica`, `georgia`, `verdana`, `trebuchet`. |
| `document.theme.content_width` | integer | No | Between 480 and 800. |
| `document.theme.radius` | integer | No | Between 0 and 32. |
| `document.theme.logo_url` | string | No | — |
| `document.theme.logo_width` | integer | No | — |
| `document.theme.logo_alt` | string | No | — |
| `document.theme.logo_align` | string | No | One of `left`, `center`, `right`. |
| `document.theme.logo_dark_url` | string | No | Logo variant shown in dark mode by clients that support it (Apple Mail, iOS); others keep `logo_url`. |
| `document.theme.button_text_color` | string | No | Label color of buttons on the brand color; empty picks white or near-black automatically. |
| `document.theme.web_font` | string | No | Google Fonts family loaded where e-mail clients support web fonts; `font` is the fallback stack. |
| `document.theme.heading_font` | string | No | Heading stack (empty = `font`). One of `system`, `inter`, `helvetica`, `georgia`, `verdana`, `trebuchet`. |
| `document.theme.heading_web_font` | string | No | Google Fonts family for headings (empty = `web_font`). |
| `document.blocks` | object[] | Yes | — |
| `document.blocks[].id` | string | No | Unique id (UUID). |
| `document.blocks[].type` | string | Yes | One of `heading`, `text`, `button`, `image`, `divider`, `spacer`, `columns`, `list`, `quote`, `code`, `social`, `footer`. |
| `document.blocks[].style` | object | No | — |
| `document.blocks[].style.align` | string | No | One of `left`, `center`, `right`. |
| `document.blocks[].style.color` | string | No | — |
| `document.blocks[].style.background` | string | No | — |
| `document.blocks[].style.font_size` | integer | No | Between 10 and 64. |
| `document.blocks[].style.padding` | object | No | — |
| `document.blocks[].level` | integer | No | One of `1`, `2`, `3`. |
| `document.blocks[].text` | string | No | — |
| `document.blocks[].runs` | object[] | No | — |
| `document.blocks[].runs[].text` | string | Yes | — |
| `document.blocks[].runs[].bold` | boolean | No | — |
| `document.blocks[].runs[].italic` | boolean | No | — |
| `document.blocks[].runs[].href` | string | No | — |
| `document.blocks[].label` | string | No | — |
| `document.blocks[].href` | string | No | — |
| `document.blocks[].full_width` | boolean | No | — |
| `document.blocks[].src` | string | No | — |
| `document.blocks[].alt` | string | No | — |
| `document.blocks[].width` | integer | No | — |
| `document.blocks[].height` | integer | No | — |
| `document.blocks[].thickness` | integer | No | — |
| `document.blocks[].columns` | object[] | No | — |
| `document.blocks[].columns[].blocks` | object[] | Yes | — |
| `document.blocks[].ordered` | boolean | No | — |
| `document.blocks[].items` | object[][] | No | — |
| `document.blocks[].links` | object[] | No | — |
| `document.blocks[].links[].network` | string | Yes | One of `x`, `linkedin`, `instagram`, `facebook`, `youtube`, `github`, `tiktok`, `discord`, `website`. |
| `document.blocks[].links[].url` | string | Yes | Public `https` URL that receives the events. |
| `document.blocks[].unsubscribe` | boolean | No | — |
| `document.blocks[].unsubscribe_label` | string | No | — |
| `document.blocks[].unsubscribe_url` | string | No | Default `{{{PIDGELY_UNSUBSCRIBE_URL}}}` (filled per recipient by broadcasts; pass it as a variable on API sends). |
| `subject` | string | No | Subject line, up to 998 bytes. Required unless a template provides it. |
| `language` | string | No | — |
| `variables` | string[] | No | Typed variables (up to 50). `FIRST_NAME`, `LAST_NAME`, `EMAIL` and `UNSUBSCRIBE_URL` are reserved. |
| `template_id` | string | No | UUID. |

## Request

This endpoint is in the Node.js SDK; the other [SDKs](https://docs.pidgely.com/sdks/) don't cover it yet, so call it over HTTP from them.

```js tab="Node.js"
import { Pidgely } from 'pidgely';

const pidgely = new Pidgely(process.env.PIDGELY_API_KEY);

const { data, error } = await pidgely.templateBuilder.ai.subjects({
  document: {
    blocks: [
      {
        type: 'heading',
        text: 'Welcome, {{{FIRST_NAME|there}}}',
      },
    ],
  },
  subject: 'Welcome to Acme',
});
console.log(data ?? error);
```

```bash tab="cURL"
curl -X POST 'https://api.pidgely.com/template-builder/ai/subjects' \
  -H "Authorization: Bearer $PIDGELY_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "document": {
    "blocks": [
      {
        "type": "heading",
        "text": "Welcome, {{{FIRST_NAME|there}}}"
      }
    ]
  },
  "subject": "Welcome to Acme"
}'
```

## Response

`200 OK`

```json
{
  "object": "template_builder",
  "data": [
    {
      "subject": "Hello from Acme",
      "preview_text": "preview_text",
      "angle": "angle"
    }
  ]
}
```

### Response fields

| Name | Type | Required | Description |
|---|---|---|---|
| `object` | string | Yes | Object type. One of `list`. |
| `data` | object[] | Yes | Items of this page. |
| `data[].subject` | string | Yes | Subject line, up to 998 bytes. Required unless a template provides it. |
| `data[].preview_text` | string | Yes | Preview text shown by mail clients next to the subject (inserted as hidden text at the top of the HTML). |
| `data[].angle` | string | Yes | — |

## Errors

Errors have the shape `{"statusCode", "name", "message"}`. See [Errors](https://docs.pidgely.com/errors/) for the full list.

| Status | Name | When |
|---|---|---|
| 401 | `missing_api_key`, `restricted_api_key` | No `Authorization: Bearer` header, or a `sending_access` key called an endpoint that needs `full_access`. |
| 403 | `invalid_api_key`, `validation_error` | The API key is invalid or revoked, or the request is not allowed for this account (unverified domain, plan limit, paused account). |
| 422 | `validation_error` | A field is missing or invalid; `message` names it. |
| 429 | `rate_limit_exceeded` | Too many requests per second. Wait for `Retry-After` seconds. |
| 502 | — | The AI service failed or returned an unusable answer (ai_unavailable, ai_busy, ai_timeout, ai_invalid_output) |