Slack message formatter
Write Slack mrkdwn with toolbar buttons and preview exactly how the message renders.
This is mrkdwn, the format Slack reads. Paste it into Slack or into an API payload.
pnpm test before merginggit pull pnpm install
Slack mrkdwn reference
Slack calls its format mrkdwn. It looks like markdown but the rules differ, so GitHub habits produce literal asterisks and pound signs.
| You type | Slack shows |
|---|---|
| *bold* | bold |
| _italic_ | italic |
| ~strike~ | strike |
| `code` | code |
| ```block``` | a multi-line code block |
| > quote | a quoted line with a gray bar |
| <https://a.com|text> | text as a link |
| :tada: | 🎉 |
What does not work in Slack
- No headings. A line starting with # stays literal text. Use *bold* on its own line instead.
- No **double asterisks** and no [text](url) links. Those are GitHub markdown, not mrkdwn.
- No tables. Post a code block or a list of lines instead.
- No real list syntax and no nested lists. Slack shows • and 1. as plain text, which still reads fine as a flat list.
How to format a Slack message
- Type or paste your message in the left pane, or edit the sample.
- Select some text and press a toolbar button to wrap it in mrkdwn: bold, italic, strikethrough, code, a quote, a list, or a link.
- Watch the preview on the right. It follows Slack rendering rules, so it shows what Slack will show.
- Press copy message, then paste it into Slack or into an API payload such as chat.postMessage.
Frequently asked questions
Is this Slack message formatter free?
Yes. It runs entirely in your browser with no account and no limit. The text never leaves your computer.
Does Slack use markdown?
No. Slack uses its own format called mrkdwn. Bold is a single *asterisk* pair, italic is _underscores_, and links are written as <url|text>. GitHub markdown habits like **double asterisks**, [text](url), and # headings do not work in Slack.
How do I preview a Slack message before sending it?
Paste the message into this tool. The preview applies Slack rendering rules for bold, italic, strikethrough, code, quotes, links, and emoji codes. If you want a check inside Slack itself, send the message to yourself in a DM first.
Why does bold text show literal asterisks in Slack?
Two common causes. You typed **double asterisks**, which Slack does not read, or the marker does not touch the text, like * bold *. Use a single asterisk on each side, directly against the first and last character.
Can I use this formatter online without installing anything?
Yes. It is a web page, and the parsing runs in your browser, so it keeps working after the page has loaded.
What formatting does Slack not support?
Headings, tables, nested lists, and inline images. A # line stays plain text. For a heading, put a short *bold* line above the paragraph. For a table, use a code block so the columns line up.
Related reading
Slack Green does one thing: it keeps your Slack presence dot green while you are actually working, so a quiet keyboard does not mark you away. Try it free.