Clef

Clef is a family of open-source decision models hosted on Workers AI designed for high-speed classification and agentic workflows.

Clef and Clef-flash are open-source decision models hosted on Workers AI that produce bounded structured outputs with probabilities. They help agents classify inputs, route tasks, and make decisions without requiring constant retraining or human intervention for every step. The models feature a vision encoder to process images and a 64k context window for large inputs. Built using a Qwen base model backbone, they utilize a non-autoregressive decision step to derive schema choices directly from internal representations. They are available on Hugging Face under an Apache 2.0 license and through a reinforcement learning fine-tuning platform.

Clef at a glance

Best for: Software engineer
Runs on: Web, API
Pricing: Free
Released: October 2026
Category: AI research tool
Website: blog.cloudflare.com

Key features

High-speed classification
Vision encoder for image inputs
64k context window
Non-autoregressive decision step
Strictly typed outputs with probabilities
Jev-API compatibility
Reinforcement learning fine-tuning platform

Use it for

Classify website domains for threat intelligence
Route customer support tickets and escalate issues
Process invoices and security incidents
Handle agentic workflows and automated decisions

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