Slack does not display rendered math. The math-with-slack script allows you to write nice-looking math using familiar TeX syntax by injecting MathJax into Slack's desktop client. This approach has several advantages over the plugin/bot solution:

• You can write both inline- and display-style equations.
• You can edit equations after you've posted them.
• Nothing is sent to external servers for rendering.

The downside is that equations are not rendered for team members without the MathJax injection.

Get and run the script. Restart the Slack client. You're done!

Windows users without Python installed can skip and jump to binary release.

There are many ways to get the script. This link to math-with-slack.py should take you to the raw file content of the script, with the version relative same as README.md that you are looking at (i.e. on the same commit). From there you can simply save the file's content to a local file math-with-slack.py (e.g. you can copy the entire content, and use your favorite editor to save the content) --- this process should be the same for all platforms, and works as long as you have a decent browser and working editor.

1. Copy the URL of link to math-with-slack.py (e.g. right click on the link -> copy URL).

2. Assuming on Mac and/or Linux, use one of the alternatives:

• With the tool curl available. Run the following in a terminal:

curl -L {PASTE_THE_COPIED_LINK_HERE} > math-with-slack.py

• With the tool wget available. Run the following in a terminal:

wget {PASTE_THE_COPIED_LINK_HERE} -O math-with-slack.py

With git available, you can also clone this repo, and access the script math-with-slack.py directly!

• MacOS and Linux

cd path/to/math-with-slack
sudo python math-with-slack.py 

The installation should take effect after restarting Slack.

• Windows You need to exit your Slack before the installation.

cd path\to\math-with-slack
python math-with-slack.py

We have also included pre-built executables for Windows in case Python is not available. Please see our Releases page for more details.

If multiple versions of Slack are found on your computer, you will be asked to select one from them.

python math-with-slack.py
Several versions of Slack were installed.
 0: /mnt/c/Users/***/AppData/Local/slack/app-4.9.0/resources/app.asar (default)
 1: /mnt/c/Users/***/AppData/Local/slack/app-4.8.0/resources/app.asar
Please select a version (#/Stop): 1

You can either enter the number indicating one of the listed versions or type Enter to select the first one.

Currently, we only support Slack installed from Slack installer. If your Slack is installed through Microsoft Store, math-with-slack is not able to modifiy files in WindowsApps folder hence not able to embedded our script.

The script needs write permissions in the Slack directory in order to inject the MathJax code. Some package and software managers write protect their directories, and math-with-slack cannot be installed if Slack is installed through such a manager. This is the case for both the Windows Store and Snap versions of Slack. You should use the version downloaded from Slack's website if you want to use math-with-slack. The script should, however, work with most package managers if you manage to grant the script write permission.

The default MathJax is of version 3.1.0 and downloaded from https://registry.npmjs.org/mathjax/-/mathjax-3.1.0.tgz, which is a registry of npmjs.

The script also works with other versions of MathJax 3 and we list a table of versions that we have tested and the corresponding URLs.

Some URLs works better for certain areas. You can use any URL in the table to install math-with-slack.

cd path\to\math-with-slack
python math-with-slack.py --mathjax-url=https://r.cnpmjs.org/mathjax/-/mathjax-3.0.5.tgz

To uninstall, run the script again with the -u flag:

python math-with-slack.py -u

The code injected by the script might be overwritten when you update the Slack app. If your client stops rendering math after an update, re-run the script as above and it should work again.

If you've installed Slack in some exotic place, the script might not find the installation by itself or it might find the wrong installation. In such cases, you need to specify the location of Slack's app.asar file as a parameter:

python math-with-slack.py --app-file=/My_Apps/Slack.app/Contents/Resources/app.asar

python math-with-slack.py --app-file=c:/Users/yourusername/AppData/Local/slack/app-4.7.0/resources/app.asar

If you are having problems that writing code like $a_k b_k$ converts _k b_ to italic font in the Slack-editor, go to Preferences → Advanced and check Format messages with markup. This should solve the problem.

As you do in TeX, use $ ... $ for inline math and $$ ... $$ for display-style math. If you need to write a lot of dollar-signs in a message and want to prevent rendering, use backslash to escape them: \$.

Note that only users with MathJax injected in their client will see the rendered version of your math. Users with the standard client will see the equations just as you wrote them (i.e., unrendered including the dollar signs).

The script allows one to customize MathJax at installation time. Currently the script allows the user to supply an optional TeX input processor option to customize the MathJax rendering. For example, to instead use \( ... \) for inline math and \[ ... \] for display-style math, and enable the package physics support, one may use the following command line arguments during installation:

python math-with-slack.py --mathjax-tex-options="{\
  packages: {'[+]': ['noerrors', 'noundefined', 'physics']}, \
  inlineMath: [['\\\(', '\\\\)']], \
  displayMath: [['\\\\[', '\\\\]']], \
}"

Note that a common scenario is when a team of people uses this plugin. In this case it will be desirable to share the same configuration for all the members.

The script alters how Slack is loaded. Under the hood, the desktop client is based on ordinary web technology. The modified client loads the MathJax library after start-up and adds a listener for messages. As soon as it detects a new message, it looks for TeX-styled math and tries to render. Everything is done in the client. Messages are never sent to servers for rendering.

Yes, please. Just add an issue or a pull request.

Thanks to past contributors:

• Caster
• chrispanag
• crstnbr
• gauss256
• jeanluct
• LaurentHayez
• NKudryavka
• peroxyacyl
• Spenhouet
• Xyene
• thisiscam
• YingzhouLi

Inspiration

This comment by jouni was extremely helpful. So was this snippet by etihwnad.