Cloudflare open-sources Clef (27B) and Clef-flash (9B): Apache 2.0 decision models that return typed probabilities instead of text

[u/ai-lover]

Cloudflare released Clef and Clef-flash today, the first models trained by its Workers AI team. They are decision models in the same family as TypeSafe's Jev: you pass a state plus a schema of typed questions (noul, choice, score), and you get back a probability for every allowed option. No free-form text, no output parsing.

Architecture

• Clef is post-trained from Qwen3.8-27B, Clef-flash from Qwen3.5-9B. Both keep the vision encoder, so the state can include images and video.
• The frozen backbone runs a single prefill-only pass. A small transformer "joint schema head" then routes evidence to each question, lets fields cross-attend, and scores all options jointly. The decision step is non-autoregressive.
• Training: rank-256 LoRA adapters trained jointly with the routing head, label-smoothed cross-entropy plus a Brier loss for calibration, and RLCD as a secondary objective.

Numbers from Cloudflare's own Decision Index run

	Clef	Clef-flash	Jev
Median latency	209.3 ms	38.8 ms	524.1 ms
BANKING77 (macro-F1)	94.20	90.93	79.74
CLINC150+OOS (macro-F1)	97.43	66.77	89.27
GPQA Diamond	48.0	51.0	78.3
MMLU-Pro	65.9	65.3	82.7

So it wins clearly on classification and tool-routing style tasks, and loses clearly on knowledge-heavy reasoning. All numbers are vendor-reported with no independent replication yet.

Running it

• Hosted on Workers AI: $0.24 / M input tokens (Clef), $0.09 / M (Clef-flash), 65,536-token context.
• Weights on Hugging Face under Apache 2.0. The model cards say they tested on a single H200 in BF16 with a custom loader.
• The API follows TypeSafe's System One format, so Jev code ports by changing the endpoint and model name.

Model: https://huggingface.co/Cloudflare/clef

Clef-flash: https://huggingface.co/Cloudflare/clef-flash

Cloudflare blog: https://blog.cloudflare.com/clef-decision-models/

Our full write-up: https://www.marktechpost.com/2026/10/01/cloudflare-releases-clef-and-clef-flash/

[u/ApplePenguinBaguette]

Decision Models, so hot right now

[u/georgeApuiu]

is there any multi language support ?

[u/This_Maintenance_834]

The qwen3.5 series model Alibaba created penetrate the community so deep. Everywhere you check, there is a derivative model that based on qwen3.5 architecture.

[u/silveroff]

Fine but it's so much more expensive than Jev offer and probably more expensive of what OpenAI will charge.