Quartzite

What it does

Quartzite is a chat interface that brings many language models into one app, including Opus 4.5, Gemini 3, GPT-5.1, DeepSeek, Perplexity AI, Llama 3 and Mistral. It adds a Markdown prompt editor, version history, cost preview, templates, variables and CSV import. You bring your own API key, so model usage is billed separately.

Quartzite is useful if you already pay for model access through API keys and want one place to write, test and compare prompts across many models. The site says you bring your own API key, so model usage is billed separately, and it states typical usage costs less than $2-3 per month. The prompt editor, version history, cost preview and template library are the main draw. A careful user should check which models their API keys cover and confirm current pricing. The site says API keys are encrypted by default and that cloud sync can be disabled for privacy. The Early Supporter Plan is listed at $3.99 per month with a lifetime price guarantee, not a one-time purchase.