# ZAYA1-8B (slim)

> ZAYA1-8B is Zyphra's open-weight reasoning model, a mixture of experts of 8.4B parameters with 760M active, trained from scratch for maths and coding. Apache 2.0. Zyphra's 4-bit build is 5.9 GB. Released SGLang and Transformers run it.

- Full: https://www.anchorterminal.com/tools/zaya1-8b.md (~8,650 tokens) · this version ~1,480 tokens · JSON https://www.anchorterminal.com/tools/zaya1-8b.json · canonical https://www.anchorterminal.com/tools/zaya1-8b
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-10 · pricing https://www.anchorterminal.com/tools/zaya1-8b#pricing · reviews https://www.anchorterminal.com/tools/zaya1-8b#reviews
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

**C · 61/100 · rank #85 of 160 open-weight models · #67 in Open-weight models · not agent-ready · confidence low**


Assessment: A small reasoning model trained from scratch by one lab, with a clean licence, 4-bit and FP8 builds and a team that answers questions. It's the hardest of the small models to run: its own architecture, a card that points at forks, and tool calling that needs a parser no release has. Little on limits, data or safety.

## Facts

- Kind: Open-weight model · vendor: Zyphra · category: Open-weight models · legal entity: Zyphra, named on the card and its site. The legal entity wasn't looked up · provenance 56/100
- Packages: huggingface `Zyphra/ZAYA1-8B`, huggingface `Zyphra/ZAYA1-8B-FP8-Experts`, huggingface `Zyphra/ZAYA1-8B-MXFP4-Experts`
- Auth: None · pricing: Free · x402: no · licence: Apache-2.0
- Benchmark probes: not run yet, so Performance is pending
- Surface graded: The open weights at huggingface.co/Zyphra/ZAYA1-8B and the FP8-Experts and MXFP4-Experts repositories beside it, read from the model card, the files and their metadata, the config, the chat template, the commit history and the runtimes' own code at their latest releases on 10 November 2026. Zyphra's home and about pages were read for who it is. The technical report, the blog post and Zyphra's forks weren't read. Nothing was downloaded or run
- Model: 8,840,488,784 parameters in the files; the card says 8.4B with 760M active. A mixture of experts with 16 experts and one active per token, trained end to end by Zyphra and post-trained for reasoning from ZAYA1-reasoning-base. ZayaForCausalLM
- Files: Four safetensors shards in BF16 (17.68 GB), chat_template.jinja, config and tokenizer files. No pickle files and no Python. The FP8-Experts repository is 9.64 GB and the MXFP4-Experts one 5.85 GB. Hugging Face lists a SHA-256 for the large files
- Licence: Apache 2.0 in the main repository's metadata. There is no LICENSE file, and the FP8-Experts and MXFP4-Experts repositories have no licence tag
- Runtimes: The card documents vLLM and Transformers from Zyphra's own forks. Released Transformers 5.22.2 has the zaya model and SGLang 0.5.23 has srt/models/zaya.py. Released vLLM 0.33.0 and llama.cpp b12242 have no code for it
- Context: Not stated on the card. config.json gives 131,072 positions
- Tools and reasoning: The card's vLLM command sets auto tool choice with a zaya_xml tool-call parser, which exists in Zyphra's fork and in no released runtime, and the qwen3 reasoning parser. The chat template takes tools and an enable_thinking switch
- Hardware: No memory figure on the card, which says the model can run on-device. Its parallel-deployment note covers 8 GPUs. The 4-bit build is 5.85 GB
- Training data: Not described on the card. The technical report wasn't read

- Scores: Capability pending, Reach 80, Risk 55, Agent interface 60, Documentation and upkeep 50 · total over the 7 assessed categories
- Why:  · Reach, Memory 30, the smallest build from Zyphra is the MXFP4-Experts repository, 5.85 GB, and 5.85 GB × 1.2 = 7.0 GB, within 16 GB. · Risk, File safety 25, safetensors only, no .bin, .pt or .pth files and no Python in the repository. · Agent interface, Chat template 20, chat_template.jinja in the repository (10,700 characters). · Documentation and upkeep, Model card 5, Intended use and the parameter counts are on the card.
- Sources: 17, open questions: 6, both in the full twin
- Capabilities: model.open-weights
- JSON: https://www.anchorterminal.com/api/v1/tools/zaya1-8b.json
- Its vendor verifies the listing with `verify_listing` or `POST https://www.anchorterminal.com/api/v1/verify` (the full twin says how); no effect on the grade.
- Support: https://www.zyphra.com; more in the full twin

## Before you call it

1. Use it for reasoning, maths and code. Don't count on tool calling outside Zyphra's vLLM fork
2. Run it with Transformers 5.22.2 or SGLang 0.5.23, which have the model built in
3. Use temperature 1.0 and top_p 0.95 in general, and temperature 0.6 for agent and code work
4. Download `Zyphra/ZAYA1-8B`, not the legacy repository, for the released runtimes
5. The quantised repositories have no licence tag. The main one is Apache 2.0

## Connect

```bash
pip install "sglang>=0.5.23"
python -m sglang.launch_server --model-path Zyphra/ZAYA1-8B --reasoning-parser qwen3
# the card's own route is vLLM from Zyphra's fork, with --tool-call-parser zaya_xml
```

```bash
# SGLang serves an OpenAI-compatible API at http://localhost:30000/v1. The card recommends temperature 1.0
# and top_p 0.95 in general, and temperature 0.6 for agent and code work
```

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## Panel reviews (0, desk reviews from public material, no calls made)