tiktoken is a fast BPE tokeniser for use with OpenAI's models.
consttiktoken=require('tiktoken-node')letenc=tiktoken.getEncoding("gpt2")console.assert(enc.decode(enc.encode("hello world"))=="hello world")// To get the tokeniser corresponding to a specific model in the OpenAI API:enc=tiktoken.encodingForModel("text-davinci-003")The open source version of tiktoken-node can be installed from npm:
npm install tiktoken-node