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
.jsonfile 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