send bold & italic text on telegram bot with html

To send bold:

1. Set the parse_mode to markdown and send *bold*
2. Set the parse_mode to html and send <b>bold</b>

To send italic:

1. Set the parse_mode to markdown and send _italic_
2. Set the parse_mode to html and send <i>italic</i>

If you are using PHP you can use this, and I'm sure it's almost similar in other languages as well

$WebsiteURL = "https://api.telegram.org/bot".$BotToken;
$text = "<b>This</b> <i>is some Text</i>";
$Update = file_get_contents($WebsiteURL."/sendMessage?chat_id=$chat_id&text=$text&parse_mode=html);

echo $Update;

Here is the list of all tags that you can use

<b>bold</b>, <strong>bold</strong>
<i>italic</i>, <em>italic</em>
<a href="http://www.example.com/">inline URL</a>
<code>inline fixed-width code</code>
<pre>pre-formatted fixed-width code block</pre>

According to the docs you can set the parse_mode field to:

• MarkdownV2
• HTML

The Markdown mode still works but it's now considered a legacy one. Use MarkdownV2 instead.

You can pass the parse_mode parameter like this:

https://api.telegram.org/bot[yourBotKey]/sendMessage?chat_id=[yourChatId]&parse_mode=MarkdownV2&text=[yourMessage]

For bold and italic using MarkdownV2:

*bold text*
_italic text_

And for HTML:

<b>bold</b> or <strong>bold</strong>
<i>italic</I> or <em>italic</em>

Make sure to encode your query-string parameters regardless the format you pick. For example:

• Java/Scala (see note on spaces):

val message = "*bold text*";
val encodedMsg = URLEncoder.encode(message, "UTF-8");

• Javascript (ref)

var message = "*bold text*"
var encodedMsg = encodeURIComponent(message)

• PHP (ref)

$message = "*bold text*";
$encodedMsg = urlencode($message);