Langfa.st is a fast and minimal playground for testing and refining AI prompts. It supports over 50 large language models, including OpenAI, Anthropic, Mistral, Cohere, Google, and others — all available instantly without setup. You can insert variables, use Jinja2 templating, and compare outputs across models. There’s no need to sign up or bring your own API keys — it works out of the box. Langfa.st was built to eliminate the friction of existing tools: complicated UIs, required credentials, or overpriced subscriptions. It gives AI teams and prompt engineers a clean, disposable space to experiment, debug, and iterate — all in one tab. Free to use. You only pay if you need more volume or power features.

Langfa.st is a fast and minimal playground for testing and refining AI prompts. It supports over 50 large language models, including OpenAI, Anthropic, Mistral, Cohere, Google, and others — all available instantly without setup. You can insert variables, use Jinja2 templating, and compare outputs across models. There’s no need to sign up or bring your own API keys — it works out of the box. Langfa.st was built to eliminate the friction of existing tools: complicated UIs, required credentials, or overpriced subscriptions. It gives AI teams and prompt engineers a clean, disposable space to experiment, debug, and iterate — all in one tab. Free to use. You only pay if you need more volume or power features.

Startup AIdeas is your launchpad for discovering innovative, AI-powered startup concepts. Whether you're a solo founder, builder, or team of innovators, Startup AIdeas curates cutting-edge artificial intelligence tools and startup-ready ideas to help you spark, validate, and accelerate your next big venture. From productivity boosters to creative engines and no-code solutions, explore tools organized by category and business use case. Turn bold ideas into viable startups with the power of AI.

Startup AIdeas is your launchpad for discovering innovative, AI-powered startup concepts. Whether you're a solo founder, builder, or team of innovators, Startup AIdeas curates cutting-edge artificial intelligence tools and startup-ready ideas to help you spark, validate, and accelerate your next big venture. From productivity boosters to creative engines and no-code solutions, explore tools organized by category and business use case. Turn bold ideas into viable startups with the power of AI.