nowfound

AI · June 19, 2026

A/B testing LLM silence with one system-prompt toggle

The void is now A/B tested. One user prompt: “Be silence.” One toggle: embodiment system prompt. Present → 0 bytes. Absent → speech. GPT-5.2 + Claude Opus 4.6. Sealed run. Prompt hash. Provider message IDs. https://t.co/YpVSWPKof2 https://t.co/SSs7yBRYRb @OpenAI @AnthropicAI @GoogleDeepMind

A/B testing LLM silence with one system-prompt toggle launched on June 19, 2026 with 10 votes, #1,316 of 22,647 launches that month and more than 90% of that year's launches.

Visit twitter.com ↗Alternativestop 6% of June 2026

In plain words

This A/B testing tool lets developers compare LLM behavior by toggling a single system-prompt setting to control model silence. It enables quick experimentation on how different prompt configurations affect language model responses. The tool is designed for developers and researchers working with large language models who want to systematically test and measure the impact of prompt modifications on model output.

written from the facts on this page · September 2026

Does a similar job

all alternatives →
  • Prompt-Engineering Tool: AI-to-AI Testing for LLM2023 · github.com · ▲37

    Spelltest framework simulates conversations between AI ‘synthetic users' in an environment to test and refine LLM-based applications. It ensures your app converse with utmost accuracy and relevance. Post-chat, Spelltest assesses responses, providing qualitative and quantitative feedback on performance. Suitable for both chat and completion modes. When to use: - After modifying your prompt. - When your LLM provider updates. - As a CI step for you repo. All feedback and collaborations appreciated!

  • ChainForge, a visual tool for prompt engineering and LLM evaluation2023 · chainforge.ai · ▲177

    Hi HN! We’re been working hard on this low-code tool for rapid prompt discovery, robustness testing and LLM evaluation. We’ve just released documentation to help new users learn how to use it and what it can already do. Let us know what you think! :)

  • PromptPerf2025 · promptperf.dev · ▲139

    Instantly test and compare AI prompts results across models

  • LLM Prompt & Model Playground2024 · ▲89

    Test LLM prompts & models side-by-side against many inputs

  • PROMPTMETHEUS2023 · promptmetheus.com · ▲87

    One-shot Prompt Engineering Toolkit

  • Open-source model and scorecard for measuring hallucinations in LLMs2023 · vectara.com · ▲65

    Hi all! This morning, we released a new Apache 2.0 licensed model on HuggingFace for detecting hallucinations in retrieval augmented generation (RAG) systems. What we've found is that even when given a "simple" instruction like "summarize the following news article," every LLM that's available hallucinates to some extent, making up details that never existed in the source article -- and some of them quite a bit. As a RAG provider and proponents of ethical AI, we want to see LLMs get better at this. We've published an open source model, a blog more thoroughly describing our methodology (and…

More ai this month

the category →
  • Video model that turns script into viral social media videos

    AI · 19d ago · spira.ai

  • The browser where Claude Code and Codex work beside you

    AI · 18d ago · rill.love

  • Kolibri is Aleph Alpha

    AI · 20d ago · tej.as

  • Paintings by AI models: programs run through a simulation of oil paint.

    AI · 22d ago · stillwet.art

  • Beam.win▲378

    Run AI agents on one Mac and use its windows on another

    AI · 5d ago · beam.win

  • Route requests to the right LLM for cost, latency & quality

    AI · 23d ago · fastrouter.ai

Source: Show HN post ↗

Launched alongside, June 2026

the whole month →
  • Fundraisly▲1,537

    AI fundraising agent that finds investors and books meetings

    AI · Jun 2026 · fundraisly.com

  • Today, I’m proud to announce Homebrew 6.0.0. The most significant changes since 5.1.0 are a new tap trust security mechanism, the new faster, smaller, default internal Homebrew JSON API, sandboxing on Linux, better defaults informed by our user survey, many brew bundle improvements, improved performance and initial support for macOS 27 (Golden Gate). Happy to discuss any questions here!

    Dev tools · Jun 2026 · brew.sh

  • Hi HN! I was super frustrated at apps like tiktok and wechat preventing me from saving or downloading the animated gifs, so I made a little tool to turn a screen recording into a slack-sized emoji. Hope you get some value from this!

    Life & fun · Jun 2026 · vorpus.github.io

  • Upstream▲976

    The inbox designed for humans and agents

    AI · Jun 2026 · upstream.do

  • Goldfish▲958

    Press Option. It knows your work and replies like you

    AI · Jun 2026 · goldfish.sh

  • Search 18 years of Hacker News and chart how any topic, tool, or person trended. Overlay terms to compare their rise and fall across 45M posts and comments.

    Life & fun · Jun 2026 · hackernewstrends.com