GainLogic
The gym companion you actually own: free, private, and easy to use.
There are hundreds of gym apps out there, but almost all of them either bombard you with recurring subscription paywalls or turn you and your workout data into an ad product. AI has made workout planning much smarter, but it introduced a brand-new nuisance: subscription fatigue. Why pay another monthly fee just for workout generation when you already pay for ChatGPT, Claude, or Gemini?
We built GainLogic out of pure frustration with that status quo. We wanted a clean, straightforward gym companion that works flawlessly offline and respects user boundaries. Instead of locking routines behind a paywall or running your logs through our servers, GainLogic lets you bring your own AI. You can generate custom training programmes on the fly directly inside the app without tedious manual typing, analyse your progression, and refresh your routines using your existing AI chats or direct API keys.
Your body weight, workout logs, and hard-earned progress are yours to keep. GainLogic stores everything locally in a private database on your device and will always remain free, ad-free, and fully local. We listen closely to community feedback to add new features, and we are working on on-device edge AI models so you can run your coaching assistant directly on your phone with zero internet required.
Key Features
Architectural Highlights
Zero subscriptions and zero tracking
Free forever with no subscriptions, paywalls, or ads. Your training logs, body measurements, and workout history never leave your phone.
Bring your own AI companion
Connect your existing AI subscriptions through a quick clipboard chat bridge, or plug in your own API keys (OpenAI, Anthropic, Google Gemini, OpenRouter) to generate and tweak routines on the fly.
Simple, distraction-free logging
Built for quick, effortless logging between sets. Works completely offline in basement gyms and dead zones with zero delay.
Edge AI on the horizon
Evolving based on community requests, including upcoming on-device edge AI models to run your workout assistant directly on your phone's hardware.
Engineering Specs
Technical Profile
Technology Stack
Support & Details
Frequently Asked Questions
Why is GainLogic free? What is in it for you? +
We built GainLogic primarily for our own workouts because we were tired of every gym app demanding recurring subscriptions or treating our personal data as a commodity. Since it costs us virtually nothing to run and we do not have central servers to maintain, we share it with the community for free.
Does GainLogic upload my workout data or body stats to your servers? +
No. We do not operate user accounts, analytics trackers, or cloud databases. All workouts, body weight logs, and personal settings remain stored in a private SQLite database strictly on your phone.
How do AI features work without a subscription, and is my data private? +
You can use your existing AI accounts via the built-in clipboard bridge, or provide your own API key (BYOK) for direct in-app generation. Your prompts travel directly from your phone to your chosen AI provider without passing through any 4DC servers. You can also disable profile sharing in settings to redact all personal stats from prompts, or connect to a local LLM (such as Ollama) for zero data transmission.
Can I use GainLogic completely offline? +
Yes. GainLogic is built offline-first. All workouts, routines, and progress histories are saved locally on your device, allowing you to train anywhere without an active internet connection.
How do I export or backup my training data? +
Navigate to Settings > Import & Export inside the app to create a full local backup or export your complete exercise history at any time as JSON or CSV.
Official Documentation & Support
Support contact: support.gainlogic@4dc.services