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Phasio
Test your LLM prompts before they break production
Phasio brings Jest-style testing to LLM prompts. Write test cases with contains, notContains, and llmJudge validators. Run evals across OpenAI and Anthropic in one command. Catch regressions in CI before your users do.
Hey PH 👋 I'm Yagnesh, co-founder at AppUnik.
I built Phasio after watching a prompt change silently break a customer-facing AI feature in production. No alert. No test. Nothing. Just users seeing garbage output.
The problem: we unit test code religiously, but prompts? We were shipping them blind.
Phasio fixes that. It's the Jest for LLM prompts — same describe/test API you already know, but for evaluating AI output. You write test cases, define validators (contains, notContains, llmJudge), and npx phasio runs them all. Exit code 1 on failure — drop it straight into GitHub Actions.
Multi-provider from day one: run the same test suite against GPT-4o-mini and Claude Haiku simultaneously. Multi-judge scoring averages results across LLMs to reduce bias.
It's open source (MIT). You bring your own API keys. No vendor lock-in.
👉 GitHub: https://github.com/YagneshKhamar...
👉 npm: npm install @phasio/sdk
👉 Docs + dashboard: https://phasio.dev
Would love your feedback — especially from anyone who's been burned by a prompt regression in prod.
About Phasio on Product Hunt
“Test your LLM prompts before they break production”
Phasio was submitted on Product Hunt and earned 0 upvotes and 1 comments, placing #140 on the daily leaderboard. Phasio brings Jest-style testing to LLM prompts. Write test cases with contains, notContains, and llmJudge validators. Run evals across OpenAI and Anthropic in one command. Catch regressions in CI before your users do.
On the analytics side, Phasio competes within Open Source, Developer Tools, Artificial Intelligence and GitHub — topics that collectively have 1.1M followers on Product Hunt. The dashboard above tracks how Phasio performed against the three products that launched closest to it on the same day.
Who hunted Phasio?
Phasio was hunted by Yagnesh Khamar. A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
For a complete overview of Phasio including community comment highlights and product details, visit the product overview.
Yagnesh Khamar