pexro

mazzarelli@gmail.com (Joey Mazzarelli) — Mon, 13 Jul 2026 00:00:00 -0600

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

Google Play — Download on Google Play (link coming soon)
Apple App Store — Download on the App Store (link coming soon)

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.

Open your LLM of choice (ChatGPT, Claude, Gemini, etc.).
Give it the following prompt:

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, and tell me to save it as a `.json` file.

Answer the model's questions. It will hand back a JSON file.
Save that output as a .json file on your device.
In pexro, upload it. The app validates it on import and shows a clear error if anything is off — fix and re-upload.

That's it. Change your training later? Ask for new JSON and upload 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:

Authoring guide (for LLMs): khtdr.com/pexro/llm.txt
JSON Schema (draft 2020-12): khtdr.com/pexro/schema.json

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KHTDR – Android

pexro

Get the app

Create your program with an LLM

For developers & LLMs