zerank
ZeroEntropyZeroEntropy's reranker line. zerank-2 is a 4B Qwen3-derived cross-encoder with a 32K context, trained through a multi-stage pipeline that models query-document relevance as adjusted Elo ratings; its card reports an average 0.6714 NDCG@10 across seven domains against 0.5847 for Cohere rerank-3.5. The earlier zerank-1 and zerank-1-small ship alongside it. Notion acquired ZeroEntropy in July 2026 and the weights were released under Apache 2.0.
Added 2026-09-11 for the embeddings_retrieval promotion. Two claims were checked rather than taken on trust, and both hold - the zerank-2 card front matter and its licence section both read apache-2.0, and ZeroEntropy's own announcement records the Notion acquisition and says all models are now open source under Apache 2.0. Note the hosted ZeroEntropy API was sunset on 2026-09-04; the weights product is unaffected and stays on the Hub, so no end_of_life is declared. Verified 2026-09-11 via the zerank-2-reranker model card and the ZeroEntropy announcement.
Openness
3 high confidence- 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.
Adoption
3 high confidenceAbout 657K downloads in the trailing 30 days across the line, almost all of it zerank-2 at 645K, with zerank-1-small at 15K and zerank-1 at 1.2K. Squarely inside the 100K-1M band on zerank-2 alone.
- https://huggingface.co/api/models/zeroentropy/zerank-2-reranker recorded 2026-09-11
downloads: 644922; gated: false; private: false; license apache-2.0 for zeroentropy/zerank-2-reranker.
Capability
4 medium confidenceRung 4, competitive frontier - a current 4B model beating the named proprietary rerankers on the publisher own seven-domain suite. Level with jina-reranker, which is the other 2025-26 frontier line here. Confidence is medium rather than high because the instrument is a vendor-constructed domain suite with no public leaderboard behind it, unlike BEIR or MMTEB.
- https://huggingface.co/zeroentropy/zerank-2-reranker/raw/main/README.md recorded 2026-09-11
Evaluations table gives zerank-2 an average NDCG@10 of 0.6714 across seven domains against 0.6456 for zerank-1, 0.5999 for Gemini 2.5 Flash listwise, 0.5847 for Cohere rerank-3.5 and 0.4509 for the OpenAI embedding retriever alone; 4B parameters, 32,768-token context.
Verified 2026-09-11