About PromptFit
PromptFit is an AI-powered workout compiler that bridges ChatGPT and a live workout renderer. Describe your session in natural language — GPT compiles a structured plan and links you directly to it.
What is PromptFit?
PromptFit is a GPT Action integration — a custom ChatGPT tool that lets you describe a workout in plain English and immediately receive a playable, animated workout session. No app to download, no account to create.
Under the hood, GPT calls the PromptFit API with a structured workout plan. The API validates the plan, assigns it a stable content-addressed ID, and returns a direct play URL. Every exercise in the plan is rendered with a two-frame animation, a countdown timer, and audio cues.
How it works
You describe the workout
Tell the PromptFit GPT what you want — target muscles, duration, available equipment, fitness level. GPT understands natural language and translates it into a structured plan.
GPT calls the API
GPT uses the PromptFit Action to POST the plan to our API. The API validates every exercise ID against a whitelist of 100 supported exercises, then returns a stable plan ID.
You start your workout
GPT returns a direct play link. Tap it on any device — phone, tablet, desktop. The workout renderer guides you through every exercise with animations, timers, and rest countdowns.
Exercise Library
PromptFit supports 100 exercises across five categories: Lower Body, Push, Pull, Core, and Conditioning. Every exercise has a unique ID, a two-frame animation, and is categorised by primary muscle group.
Browse the full exercise library →For Developers
The PromptFit API is open. You can POST a workout plan JSON to /api/get-plan-id and receive a stable, shareable play URL. Plans are content-addressed (SHA-256 Base62) and cached for 30 days with sliding expiration.