---
title: "Introducing Clef: our open-source decision models, and new RL fine-tuning platform"
description: "Cloudflare released two open-source decision models, Clef and Clef-flash, hosted on Workers AI under an Apache 2.0 license and fully compatible with the Jev API. These models produce bounded structured outputs for agentic workflows, classifying inputs like customer support messages or website domains with typed probabilities and confidence scores. Clef includes a vision encoder and a 64k context window, distinguishing it from text-only decision models such as Jev, and currently leads the Jev Decision Index benchmark. The models demonstrated lower latency than alternatives, with Clef classifying a website in 2.2 seconds versus 4.7 seconds for Cloudflare’s fastest general LLM, while Clef-flash offers even faster inference at 38.8 ms median latency. Cloudflare also debuted a reinforcement learning fine-tuning platform that lets customers adapt Clef to their specific use cases using their own data."
---

# Introducing Clef: our open-source decision models, and new RL fine-tuning platform

[Cloudflare](https://yomu.fyi/company/cloudflare) · Kevin Flansburg · Oct 1, 2026

**Type:** Announcement

## Summary

Cloudflare released two open-source decision models, Clef and Clef-flash, hosted on Workers AI under an Apache 2.0 license and fully compatible with the Jev API. These models produce bounded structured outputs for agentic workflows, classifying inputs like customer support messages or website domains with typed probabilities and confidence scores. Clef includes a vision encoder and a 64k context window, distinguishing it from text-only decision models such as Jev, and currently leads the Jev Decision Index benchmark. The models demonstrated lower latency than alternatives, with Clef classifying a website in 2.2 seconds versus 4.7 seconds for Cloudflare’s fastest general LLM, while Clef-flash offers even faster inference at 38.8 ms median latency. Cloudflare also debuted a reinforcement learning fine-tuning platform that lets customers adapt Clef to their specific use cases using their own data.

## Context

Cloudflare introduces Clef and Clef-flash, open-source decision models hosted on Workers AI, and a new RL fine-tuning platform for customizing these models.

## Approach / What changed

Cloudflare trained Clef models by adapting DiffusionGemma to output deterministic probabilities, using supervised fine-tuning and reinforcement learning, and built a fine-tuning platform with AI Gateway, Containers for RL sandboxes, and Workers AI redeployment.

## Takeaways

- Clef and Clef-flash are open-source decision models hosted on Workers AI, fully Jev-API compatible, and available under an Apache 2.0 license.
- Clef includes a vision encoder and a 64k context window, enabling classification of images and longer inputs, unlike text-only decision models such as Jev.
- The RL fine-tuning platform integrates AI Gateway for data capture, Containers for RL sandboxes, and Workers AI redeployment, allowing customers to fine-tune Clef with their own data.

## FAQ

### How does Clef differ from Jev?

Clef has a vision encoder and a 64k context window, while Jev is text-only with a 32k context window. Clef also leads the Jev Decision Index benchmark and offers lower latency.

### What is the latency of Clef models?

Clef has a median latency of 209.3 ms and p95 of 238.6 ms. Clef-flash is faster with 38.8 ms median and 122.4 ms p95, compared to Jev's 524.1 ms median.

### How can I fine-tune Clef for my use case?

Cloudflare offers a reinforcement learning fine-tuning platform that uses AI Gateway to capture your request/response data, Containers for RL sandboxes to score and replay agent actions, and Workers AI to redeploy the fine-tuned model.

**Tags:** [Decision Models](https://yomu.fyi/topic/decision-models), [Open Source](https://yomu.fyi/topic/open-source), [Reinforcement Learning](https://yomu.fyi/topic/reinforcement-learning), [Workers AI](https://yomu.fyi/topic/workers-ai)

- Source: [Cloudflare](https://blog.cloudflare.com/clef-decision-models)
- Source URL: https://blog.cloudflare.com/clef-decision-models
- Ingested by Yomu: 2026-10-01T18:00:08.126Z

[Read original post](https://blog.cloudflare.com/clef-decision-models)