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Slack Big Emoji

Slack Big Emoji is a ruby command-line tool (see support) that helps out with the generation of big emojis to a Slack team.

See What's a Big Emoji? for more information.


Make sure you're using Ruby 2.4.0 (will support native OS X version soon) and you have a working installation of ImageMagick.

About images:

  • Tool can only process static image files (only png, jpg, jpeg).
  • Images must be square or hold a w/h ratio of 1.0, this is going to be validated.
  • No GIF support since Slack's limit is 64kb and it's a pain to generalize optimization.


Installation is done through RubyGems, to install run:

$ gem install slack-big-emoji

Once completed you should be ready to go.


First, locate a square image and run:

$ slack-big-emoji liarliar.jpg

The script will resize and crop the image into tiles and upload them all (through a small wizard) to your team's Slack.

You can also run slack-big-emoji --help for more options.

What's a Big Emoji?

Big emojis are a set of multiple emojis combined in a grid that together displays a big image.

— Probably you: What?

— Me, probably: Why not?

— You: I mean, what's a Slack Big Emoji?

A Bigger Emoji™.

With this tool you'll be able to turn this Jim Carrey snapshot from the movie Liar Liar:

Picture of Jim Carrey's teeth in the movie "Liar Liar"

Into a set of emoji codes like this one:


Once posted in Slack will look like this (mobile looks shitty, tho):

Advanced Installation & Usage

This gem can be used from an application too, add this line to your Gemfile:

gem 'slack-big-emoji'

And then execute:

$ bundle install

For example, this is the minimal setup for a command-line tool:

require 'slack-big-emoji'
# require 'slack-big-emoji/cli'

# Sets up option parser coming from ARGV
cli =

# Converter takes as args the file and conversion options
emoji =

# The uploader takes care to upload a folder full of images
uploader =

# The CLI generates a grid based on the output filename,
# this is the grid to be used in Slack to see the full emoji

Further documentation can be read in code.


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.


Command-line tool to create big emojis for Slack.







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