tiktoken is a BPE tokeniser for use with OpenAI's models. This is a pure JS port of the original tiktoken library.
Install the library from NPM:
npm install js-tiktoken
You can only load the ranks you need, which will significantly reduce the bundle size:
import { Tiktoken } from "js-tiktoken/lite";
import o200k_base from "js-tiktoken/ranks/o200k_base";
const enc = new Tiktoken(o200k_base);
assert(enc.decode(enc.encode("hello world")) === "hello world");Alternatively, encodings can be loaded dynamically from our CDN hosted on Cloudflare Pages.
import { Tiktoken } from "js-tiktoken/lite";
const res = await fetch(`https://tiktoken.pages.dev/js/o200k_base.json`);
const o200k_base = await res.json();
const enc = new Tiktoken(o200k_base);
assert(enc.decode(enc.encode("hello world")) === "hello world");If you need all the OpenAI tokenizers, you can import the entire library:
[!CAUTION] This will include all the OpenAI tokenizers, which may significantly increase the bundle size. See
import assert from "node:assert";
import { getEncoding, encodingForModel } from "js-tiktoken";
const enc = getEncoding("gpt2");
assert(enc.decode(enc.encode("hello world")) === "hello world");