ttok 1.0

# Release: ttok 1.0 Source: [https://simonwillison.net/2026/Oct/9/ttok/](https://simonwillison.net/2026/Oct/9/ttok/) I released[ttok 0\.4](https://simonwillison.net/2026/Oct/8/ttok/), ran`uv tool upgrade ttok`, piped a file into the new version\.\.\. and realized that it was defaulting to the GPT\-4 tokenizer when it should very clearly default to GPT\-5/GPT\-6 instead\! I figured switching the default was a reasonable excuse to finally ship a 1\.0\. OpenAI haven't actually confirmed that GPT\-6 uses the same tokenizer as the GPT\-5 family yet \- there's an[angry issue about it](https://github.com/openai/tiktoken/issues/608)\- but I found[this commit](https://github.com/williamliu-ai/token-count-compare/commit/8d8a2178538bb37beb548fc37378135e4ff4b0c8)by William Liu which reports on an experiment he ran confirming that the tokenizers are likely the same: > All seven GPT models \(5\.5, 5\.6 Sol/Terra/Luna, 6 Astra/Sol/Luna\) report 44,794 tokens and match each other on every one of the 31 fixtures\. GPT\-6 introduces no input\-count change on this corpus\.