Trying to gain weight?
You know how it goes. You struggle to eat enough. You write another shopping list. You meal prep on Sunday and watch it die in the fridge by Wednesday. You log every bite trying to hit a surplus. And you're not even sure when this bulk is supposed to end.
JSON.fit was built by a busy skinny guy who was sick of all of that.
Pick the calorie-dense meals you actually want to eat, paste one prompt into ChatGPT or Claude, and import a full week: meals matched to your exact macros, a priced shopping list, and a meal-prep plan that gets the cooking done in one session. It runs on the AI you already have instead of ours... so there's no subscription.
Bulking is simple: eat big, hit your protein, train hard. Doing it consistently around work and a real life is the hard part. JSON.fit makes eating enough the easy part, so you can hit your numbers and get back to your life.
WHAT YOU GET
- A route from your body today to your goal: when to bulk, when to cut, and roughly when you'll arrive
- Calorie-dense meals that are actually easy to make, with exact ingredients and every step
- AI meal plans dialled to your bodyweight, goal and macros
- Foods you pick yourself, from a deep rotation so you never get bored
- A shopping list priced and sorted for your store
- A meal-prep guide that turns the week's cooking into one session
- Tracking that's ticking off planned meals, not logging every bite
- Training programs built for bulking that run a full year, fully tracked
- Works with ChatGPT, Claude, Gemini, DeepSeek and more
WHY THERE'S NO SUBSCRIPTION
Most fitness apps run AI on their own servers and charge $10–20 a month for it. JSON.fit uses the AI you already use, so there's no cost to pass on and you're never locked into one provider.
No subscription. No ads. No catch.
YOUR DATA STAYS YOURS
No accounts. No tracking. Your nutrition and workout data never leaves your device.
BUILT BY A SKINNY GUY, FOR SKINNY GUYS
The creator uses JSON.fit to run his own bulks and cuts. The bulk/cut route, the meal rotation, the prep guide, they all exist because he needed them. Follow the plan, swap meals when you want variety, and the app tells you when to bulk, when to cut, and updates your targets as your body changes, guidance grounded in current evidence on muscle gain. Updates ship as he finds better ways to do it.
Download JSON.fit and stop guessing what to do next.
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