Quartzite

Quartzite is a web and desktop (Mac, Windows) AI productivity app and Prompt IDE for developers, teams, and creators who work with multiple large language models in complex workflows.

Key capabilities include:

• Unified multi-model chat for running prompts against models such as GPT-4-class options, Gemini, Claude, Perplexity, and more from one interface (bring your own API key).
• Advanced Markdown prompt editor with draft mode and autosave, plus support for structured prompts and code snippets.
• Version history and comparison to iterate on prompts and model settings, then review changes and roll back when needed.
• Templates, variables, and CSV import to build reusable prompt libraries and generate many prompt variants quickly.
• Cost preview to estimate token usage and run costs before submitting a prompt, plus data export for prompts and outputs.

Pricing: Early Supporter Plan is $3.99/month for platform access (discounted from $7.99/month) plus pay-per-use model costs via the user’s API key (often reported as ~$2 to $3/month for typical usage).

What makes it notable is its focus on prompt development tooling, including versioning, templating, and cost estimation, while providing a single workspace to test and compare outputs across multiple LLM providers instead of committing to one chat subscription.