ZeroEntropy

weights

open(Apache-2.0 ungated safetensors for zerank-1, zerank-1-small and zerank-2)

data

closed(the Elo-based relevance pipeline is described in arXiv 2509.12541

code

closed(no training or model repository

license

Apache-2.0(OSI)

Both claims that came with this product were checked rather than assumed, and both hold. The zerank-2 card states Apache-2.0 in its front matter, its Model Details table and a closing License section; ZeroEntropy own announcement records the Notion acquisition and says all its models are now fully open source under Apache 2.0. No corpus and no code, so an OSI licence over downloadable weights lands on the open-weights fallthrough.

• https://huggingface.co/zeroentropy/zerank-2-reranker/raw/main/README.md recorded 2026-09-11

  Front matter reads license: apache-2.0, base_model Qwen/Qwen3-4B; the Model Details table records License Apache-2.0 and the closing License section repeats it. Training is described as a multi-stage Elo-rating pipeline with a link to arXiv 2509.12541; no corpus or training code is offered.

• https://huggingface.co/zeroentropy/zerank-1-reranker/raw/main/README.md recorded 2026-09-11

  Front matter for zerank-1 also reads license: apache-2.0, confirming the terms are consistent across the distributed SKUs rather than new with zerank-2.

• https://zeroentropy.dev/articles/zeroentropy-is-joining-notion/ recorded 2026-09-11

  ZeroEntropy announcement dated 2026-07-24: "ZeroEntropy has been acquired by Notion", "All of our models are now fully open-source under Apache 2.0", and all ZeroEntropy products remain supported until September 4th, 2026 after which they are sunset.