Tools for AI API developers
Small, focused, no-signup tools that answer a concrete question fast. Everything runs in your browser — your data never leaves your device. More are on the way.
- Tokens
Token counter
Paste text, pick a model, and see exact tokens, characters, and chars/token — every token as a colored chip with its ID.
- Cost
LLM API cost calculator
Real token counts → dollar cost, split into input vs output, for the model you pick. Paste text to auto-count input.
- Cost
Model cost comparison
One prompt + expected output length, costed side by side across every model in a sortable table.
- Tokens
Tokenizer visualizer
See exactly how text splits into tokens, color-coded, with hover to inspect each token's ID and boundaries.
- Tokens
Context window checker
Paste a prompt, pick a model, and find out whether it fits the context window — and how many tokens are left.
- Tokens
Word ↔ token estimator
Quick two-way converter between word count and token count, with real-tokenizer calibration.
- Explainer
From prompt to output
A clickable pipeline explaining how an LLM turns your prompt into output — tokenization, embeddings, transformer, sampling, and back.
- Cost
AI API Cost Calculator (monthly)
Estimate and compare monthly spend across the latest OpenAI, Anthropic, Gemini, and DeepSeek models by your request volume. Highlights the cheapest option.
- Tokens
JSON to TOON Converter
Convert JSON to TOON (Token-Oriented Object Notation) to cut LLM prompt tokens. Live token and character savings, runs entirely in your browser.
- Tokens
TOON to JSON Converter
Decode TOON (Token-Oriented Object Notation) back into standard, pretty-printed JSON. Handles tabular arrays, nesting, and custom delimiters, all in your browser.