Gem Version


Tiktoken is BPE tokenizer from OpenAI used with their GPT models. This is a wrapper around it aimed primarily at enabling accurate counts of GPT model tokens used.


Install the gem and add to the application's Gemfile by executing:

$ bundle add tiktoken_ruby

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install tiktoken_ruby


Usage should be very similar to the python library. Here's a simple example

Encode and decode text

require 'tiktoken_ruby'

enc = Tiktoken.get_encoding("cl100k_base")
enc.decode(enc.encode("hello world")) #=> "hello world"

Encoders can also be retrieved by model name

require 'tiktoken_ruby'

enc = Tiktoken.encoding_for_model("gpt-4")
enc.encode("hello world").length #=> 2


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at

To get started with development:

git clone
cd tiktoken_ruby
bundle install
bundle exec rake compile
bundle exec rake spec


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