This is a pure go port of OpenAI's tokenizer.

package main

import (
    "fmt"
    "github.com/tiktoken-go/tokenizer"
)

func main() {
    enc, err := tokenizer.Get(tokenizer.Cl100kBase)
    if err != nil {
        panic("oh oh")
    }

    // this should print a list of token ids
    ids, _, _ := enc.Encode("supercalifragilistic")
    fmt.Println(ids)

    // this should print the original string back
    text, _ := enc.Decode(ids)
    fmt.Println(text)
}

Alternatively you can use the included command-line tool

> tokenizer -h

Usage of tokenizer:
  -decode string
        tokens to decode
  -encode string
        text to encode
  -token string
        text to calculate token

> tokenizer -encode supercalifragilistic

• ✅ port code
• ✅ cl100k_base encoding
• ✅ r50k_base encoding
• ✅ p50k_base encoding
• ✅ p50k_edit encoding
• ✅ tests
• ❌ handle special tokens
• ❌ gpt-2 model

This library embeds OpenAI's vocabularies—which are not small (~4Mb)— as go maps. This is different than what the way python version of tiktoken works, which downloads the dictionaries and puts them in a cache folder.

However, since the dictionaries are compiled during the go build process the performance and start-up times should be better than downloading and loading them at runtime.

Here is a list of other libraries that do something similar.

• https://github.com/sugarme/tokenizer (A different tokenizer algorithm than OpenAI's)
• https://github.com/pandodao/tokenizer-go (deprecated, calls into JavaScript)
• https://github.com/pkoukk/tiktoken-go