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pexro (Personal EXercise ROutine) is a personal mobile app that runs and tracks exercise programs described by uploaded JSON. No workout is hard-coded — the app is a generic interpreter over a schema. Describe a routine once, upload it, and pexro guides you through each session and tracks your progress over time.

Get the app

Create your program with an LLM

pexro doesn't ship a fixed routine — it runs a JSON program file you upload. The easiest way to make one is to let a language model write it for you.

  1. Open your LLM of choice (ChatGPT, Claude, Gemini, etc.).
  2. Give it the following prompt (use the Copy button, then paste it into the chat):
I want you to build me a personal exercise program for a mobile app called pexro. First, read the authoring guide and JSON schema at https://khtdr.com/pexro/llm.txt and follow it exactly. Then ask me about my goals, experience level, available equipment, any injuries, and how many days per week I want to train — before writing anything. Finally, output a single valid JSON program file that conforms to the schema, inside a code block so I can copy it. I'll import it into pexro either by pasting the JSON straight from this chat or by saving it as a .json file, so make sure the whole program is in one self-contained block.
  1. Answer the model's questions. It will hand back a JSON program.

  2. Import it into pexro one of two ways:

    • Paste from clipboard — copy the JSON out of the chat and paste it directly into pexro. No file needed.
    • From a file — or save the output as a .json file on your device and upload that.
  3. Either way, the app validates the program on import and shows a clear error if anything is off — fix and re-import.

That's it. Change your training later? Ask for new JSON and import it again — your logged history is kept separate and carries over.

For developers & LLMs

The full authoring guide, a complete example, and the machine-readable schema live in plain text:

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