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

# Character Limits

> Text, caption, title, and description limits for every Postsiva platform — enforced at 422 on exceed.

Postsiva validates text length **before** posting. Over-limit text returns HTTP **422** with the platform name and character count.

## Primary limits (captions / post text)

| Platform          | Limit      | Field(s)                                               | Post types                   |
| ----------------- | ---------- | ------------------------------------------------------ | ---------------------------- |
| LinkedIn          | **3,000**  | `default_text`, `linkedin_text`, `linkedin_page_texts` | Text, image, video, carousel |
| Facebook          | **63,206** | `default_text`, `facebook_page_texts`                  | Text, image, video, carousel |
| Threads (text)    | **500**    | `default_text`, `threads_text`                         | Text only                    |
| Threads (caption) | **2,200**  | Caption on image, carousel, video                      | Image, carousel, video       |
| Instagram         | **2,200**  | `default_text`, `instagram_text`                       | Image, carousel, video       |
| TikTok            | **2,200**  | `default_text`, `tiktok_text`                          | Video, image, carousel       |
| Bluesky           | **300**    | `default_text`                                         | Text, image, carousel, video |
| YouTube           | —          | See title/description below                            | Video only                   |

## Secondary limits (titles / descriptions)

| Platform       | Field                                    | Limit                    |
| -------------- | ---------------------------------------- | ------------------------ |
| YouTube        | `youtube_title` / `default_text` (title) | **100**                  |
| YouTube        | `youtube_description`                    | **5,000**                |
| Pinterest      | `pinterest_text` (pin title)             | **100**                  |
| Pinterest      | `pinterest_description`                  | **500**                  |
| TikTok (photo) | `tiktok_title`                           | **90** UTF-16 code units |

## Multi-platform posting

When posting to multiple platforms, **each platform is validated independently**. A caption valid for LinkedIn (3,000) may fail on Bluesky (300):

```json theme={null}
{
  "platforms": ["linkedin", "bluesky"],
  "default_text": "A 400-character caption..."
}
```

Returns `422` for Bluesky even if LinkedIn would succeed.

<Tip>
  Use platform overrides to send different lengths per destination:
  `threads.threads_text`, `instagram.instagram_text`, etc.
</Tip>

## Example: platform-specific text

```json theme={null}
{
  "platforms": ["linkedin", "threads", "bluesky"],
  "default_text": "Full LinkedIn article-style post with details...",
  "threads": {
    "threads_text": "Medium-length Threads post under 500 chars."
  },
  "bluesky": {}
}
```

For Bluesky, trim `default_text` to 300 chars or add a shorter override in a pre-processing step.

## Error format

```json theme={null}
{
  "detail": "Max text character limit for threads is 500. Received 612 characters in threads_text/default_text."
}
```

Per-page LinkedIn/Facebook maps show the key in the label:

```json theme={null}
{
  "detail": "Max text character limit for linkedin is 3000. Received 3100 characters in linkedin_page_texts[108813535]."
}
```

## Quick reference by use case

| Use case                         | Safe default length     |
| -------------------------------- | ----------------------- |
| Cross-post to all text platforms | **300** (Bluesky floor) |
| LinkedIn + Facebook only         | **3,000**               |
| Threads text post                | **500**                 |
| Instagram / TikTok caption       | **2,200**               |
| YouTube title                    | **100**                 |
| Pinterest pin title              | **100**                 |

## Related

<CardGroup cols={2}>
  <Card title="Platforms overview" href="/platforms/overview">All eight platforms</Card>
  <Card title="HTTP errors" href="/errors/http">422 validation errors</Card>
</CardGroup>