LangFast
LangFast is an online LLM playground for testing and evaluating AI prompts. Users bring their own API keys to run prompts across multiple language models, compare outputs…
About LangFast
LangFast is an online LLM playground for testing and evaluating AI prompts. Users bring their own API keys to run prompts across multiple language models, compare outputs side-by-side, and validate results with test cases. It includes prompt version history, dynamic variables and Jinja2 templates, structured outputs, function calling, and shareable links for collaboration. Access is sold as one-time payment plans (1-year or lifetime) rather than a recurring subscription, and API costs are paid separately via the user's own keys.
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