Tools

Free developer tools for AI engineers

Small, focused tools I use while building AI features. They run in your browser and need no signup.

• Token Counter

  Count tokens for any text, exactly for OpenAI models and estimated for Claude, in your browser.

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• Claude Token Counter

  Estimate Claude tokens and input cost for a prompt, with the limits of estimating spelled out.

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• OpenAI Token Counter

  Exact o200k_base token counts for GPT-style prompts, computed locally.

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• Agent Framework Picker

  Five questions to decide between a plain loop, an SDK, or a framework.

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• LLM Cost Calculator

  Estimate what an LLM feature costs per request, per day and per month from your own token counts and prices.

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• Agent Run Budget Simulator

  See how an AI agent's cost grows turn by turn and where your budget cap would stop it.

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• JSON to Zod

  Paste a JSON sample or a JSON Schema and get a Zod schema and TypeScript types, in your browser.

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• Tool Schema Validator

  Check an OpenAI, Anthropic or MCP tool definition for common mistakes and convert it to the other two formats.

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