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

# Writing the post

> The editor, formatting, mentions, emoji and character counts

**Where:** Inside the composer, the left column

## The editor changes per platform

Postiz offers different formatting depending on what the selected platform
accepts. You are not seeing an inconsistent interface, you are seeing what that
platform can carry.

| Editor   | Toolbar                                     | Used by                                 |
| -------- | ------------------------------------------- | --------------------------------------- |
| Plain    | Emoji and signature only                    | Platforms that render text as-is        |
| Standard | Bold, underline, emoji, signature           | Most social platforms                   |
| Markdown | Adds links, bullet lists, headings H1 to H3 | Discord, Medium, Dev.to, Hashnode, Whop |
| HTML     | Rich formatting                             | X, WordPress, Listmonk                  |

Telegram is a special case: it takes markdown but not headings, so the heading
buttons are hidden.

## Character counts

The counter under the editor shows the limit for the selected channel, and it
is media-aware, so attaching an image can change the number on platforms that
charge characters for links or media.

Limits vary enormously: Bluesky 300, X 280 (4,000 verified, 100,000 in article
mode), Mastodon 500, LinkedIn 3,000, Facebook 63,206. The full list is in
[Posting rules by platform](/general/platforms/overview).

If you are over the limit on one channel only, detach that channel rather than
cutting the text everywhere. See
[Global vs per-channel](/general/composer/global-vs-per-channel).

## Mentions

Type `@` to mention someone. Postiz queries the platform for matching
accounts and inserts a real mention, not just text.

<Note>
  Mentions only work on a **detached channel**. In the Global tab there is no
  single platform to resolve the handle against, so the suggestion list does not
  appear.
</Note>

## Emoji

The emoji picker sits in the toolbar and follows your light or dark theme. You
can also paste emoji directly.

## Signatures

The signature button inserts a saved block of text. If one of your signatures
is marked auto-add, it is already in the editor when the composer opens.

Manage them in Settings, see [Sets and signatures](/general/settings/reusables).

## Links

Postiz validates links as you type and rejects `ftp:`, `file:` and `mailto:`
schemes, plus anything that looks like a bare email address.

What happens to the links you do add depends on your short link preference and
the platform. See [Links and validation](/general/composer/links-and-validation).

## Undo

The editor keeps 100 steps of undo history. Closing the composer discards
everything, so save a draft if you are not finished.