Cloudflare Clef and Clef-flash Open-Source Decision Models
Cloudflare released two Cloudflare-trained decision models, Clef and Clef-flash, on 1 October 2026, hosted on Workers AI and open-sourced under Apache 2.0, alongside its first reinforcement-learning fine-tuning product.
Tool Overview
Features, steps and FAQ below
Features
- ✓ Cloudflare says Clef is a decision model that returns typed answers with probabilities (such as choice and score) rather than generating text, letting agents make programmatic decisions without necessarily keeping a human in the loop, for example judging whether a support message is urgent and which team should handle it
- ✓ Cloudflare says Clef has a vision encoder so it can classify visual content such as images, and has a 64k context window (Cloudflare compares this with Jev's 32k) to hold more input state
- ✓ Cloudflare says Clef and Clef-flash are fully Jev-API compatible so they can be swapped in easily; the larger Clef targets precision while Clef-flash targets latency-critical decisions (Cloudflare reports median latency of about 209.3ms and 38.8ms respectively)
- ✓ Cloudflare says both models are open-sourced on Hugging Face under Apache 2.0 for local experimentation and are hosted on Workers AI edge GPUs to reduce network latency
- ✓ Cloudflare is also debuting its reinforcement-learning (RL) fine-tuning product so customers can fine-tune Clef with their own data; Cloudflare says it does not read, store or train on customer requests or responses unless they choose to use the fine-tuning product
How to Use
- Open the Workers AI Clef model page in Cloudflare's developer documentation, or download the open weights from Hugging Face (huggingface.co/Cloudflare/clef)
- Call Clef through the Workers AI REST API; Cloudflare's example uses curl to POST to /ai/run/@cf/cloudflare/clef with your account ID and auth token
- Pass the input as state and define questions with types such as choice and score; the model returns typed answers with probabilities
- For specialized needs, use Cloudflare's new RL product to fine-tune Clef on your own data and redeploy the fine-tuned model on Workers AI
FAQ
What is Clef?
One of two Cloudflare-trained decision models released on 1 October 2026, which Cloudflare describes as returning typed answers with probabilities rather than generating text, hosted on Workers AI and open-sourced under Apache 2.0.
How is Clef different from Jev?
Cloudflare says Clef has a vision encoder so it can classify visual content like images (Jev today only does text classification), has a 64k context window (Jev has 32k), and is fully Jev-API compatible.
What is the difference between Clef and Clef-flash?
Cloudflare says the larger Clef targets higher-precision decisions while Clef-flash targets latency-critical decisions; Cloudflare reports median latency of about 209.3ms for Clef and 38.8ms for Clef-flash.
Is Clef open source?
Cloudflare says both models are open-sourced on Hugging Face (huggingface.co/Cloudflare/clef) under an Apache 2.0 license for local running and experimentation.
How do I fine-tune Clef?
Cloudflare says it is debuting an RL fine-tuning product that lets customers fine-tune Clef with their own use cases and data and redeploy the fine-tuned model on Workers AI.