Quartzite

Quartzite is a browser-based chat interface built by CMD Shift Studio to make working across multiple language models easier for research, writing, and development tasks. Instead of subscribing separately to each provider, users bring their own API keys and switch between models like Claude, GPT-5, Gemini, DeepSeek, and others from one workspace. The interface centers on a markdown prompt editor with draft saving and version history, so users can iterate on a prompt and compare how different versions or model configurations perform. A cost preview estimates token usage and price before a prompt actually runs, which helps avoid surprise charges when testing on premium models. Additional tools include a template repository for reusable prompts, support for prompt variables, CSV import for batch operations, and export of prompts and outputs to file. API keys are encrypted by default, and users can disable cloud sync to keep data stored only in the browser. Quartzite suits developers, researchers, and writers who want one place to draft and compare prompts across providers rather than juggling separate tabs and subscriptions. Since users supply their own model API keys, usage costs still depend entirely on each provider's own pricing, and the tool itself is billed on a separate low-cost subscription.