I decided to bite the bullet and built one for NodeJS - GitHub - xanthous-tech/gpt3-tokenizer: Isomorphic Tokenizer for GPT3 algorithm for OpenAI.
I have incorporated the best from what is out there and followed the minified code from the OpenAI tokenizer demo page. Currently it supports NodeJS but I should be able to quickly make it available on browser (the same as the token counting on playground). It should also properly count tokens for codex models since it is merging continuous spaces as single token.