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

# Composer: content, previews, threads, and first comments

> Compose posts per channel, preview how they render on each platform, build threads, and add first comments.

The composer is where you write content for one or more channels at once. Beyond the basic text editor it supports per-channel content, per-platform previews, threads, and first comments.

## Global vs. per-channel content

By default the composer uses a **global** body shared by every selected channel. Switch to **per-channel** mode to write a different body for each platform - useful when platforms have different tone or formatting norms.

## Per-platform preview

As you type, the composer renders a live preview matching each target platform's layout. Preview families cover microblogs, video, Instagram, LinkedIn, Facebook, articles, email, and community posts, so you can catch layout issues before scheduling.

## Provider settings

Some providers accept per-channel settings beyond the text - for example image counts or platform-specific options. These appear in the composer when you select the channel and are validated before publishing.

## Threads

A thread is a series of linked posts published together. In the composer, add thread parts below the main body; each part is rendered as its own post and grouped together. Thread parts can also be provided through the CSV import (`thread` column) and are grouped with the main post.

## First comment

Optionally set a **first comment** that PostSider publishes right after the main post, where the platform supports it. Instagram creators commonly use this for hashtags. The first comment is published best-effort by the publishing workflow; Threads requires the `threads_manage_replies` scope. You can also supply it via the public API (`posts[].firstComment`) or the CSV import (`first_comment` column).

## Reusable content

Use the [composer helpers](/features/composer-helpers) panel to insert saved hashtag groups, caption templates, and UTM presets.