AI tools
Count tokens, check context fit, estimate API costs, format fine-tuning files, and read chat exports — exact where an OpenAI tokenizer exists, labeled estimates where one doesn't. Everything runs in your browser; exports never leave the tab.
- Tokenizer playground
Count and inspect OpenAI tokens — o200k, cl100k, p50k, r50k, in a worker.
- Context fit
Does your prompt fit? Exact OpenAI counts; labeled estimates for any other model.
- API cost estimator
What a prompt costs to run — dated price data, exact arithmetic, tiers applied.
- Fine-tune JSONL formatter
Validate and format training files — target presets, per-line errors, loss ledger.
- Chat export viewer
Read a ChatGPT export or JSONL log — virtualized, local, nothing sent anywhere.
- Chat template renderer
Render a transcript to ChatML, Llama, Mistral, or Gemma format — with token counts.
6 tools · everything is computed locally, nothing leaves your device.