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Consider these factors when choosing a base model:
  • Training mode: Every model supports low-rank adapter (LoRA) training. Not every model supports full-weight training. Check the Training modes column in the catalog, or list models programmatically.
  • Context length: The trainer’s maximum sequence length differs between LoRA and full-weight training.
  • GPU type: Post-training currently runs only on B200 GPUs (B200-SXM). Support for B300 and GB300 GPUs will be added soon.
  • Adapter capacity: Each resource caps how many LoRA sessions it accepts at once, which matters if you plan to train several adapters together.
Start with Qwen/Qwen3.8-27B to get your training loop working, then scale up once it runs.
The post-training service currently only supports text models. To fine-tune on images, use vision fine-tuning.

Catalog

This table lists the public B200 configurations and syncs daily from /v1/rl/supported-models. For the live catalog, list the models programmatically. How to read the columns:
  • Training modes: Every model lists LoRA. Models that also list full support full-weight training. For the others, use lora_enabled=True.
  • Max context: The longest sequence (prompt plus response) that one forward_backward sample can hold.
  • Generator context: The longest sequence (prompt plus completion) that a sample call can handle. Where it’s larger than Max context (LoRA), keep GRPO rollouts within the trainer’s limit, because forward_backward rejects longer samples.
  • LoRA sessions per resource: The number of adapter sessions one resource accepts at once. The service catalog sets this limit per model and per GPU type. The API doesn’t return it yet, so this column is maintained by hand. To train several adapters on one resource, see Train multiple adapters on one base model.

Single-session variants

The following models also support single-session variants for better throughput. These variants support LoRA training only and accept a single LoRA adapter, so each resource can run only one training session at a time.
  • Qwen3.6 35B A3B: Qwen/Qwen3.6-35B-A3B-single-session.
  • Qwen3.8 27B: Qwen/Qwen3.8-27B-single-session.

List supported models programmatically

To list the live B200 configurations:
The output has one block per model, like this:
To run a similar listing from a cookbook checkout, use uv run python scripts/supported_models.py.

Choose a GPU type

Set gpu_type="B200-SXM" inside ComputeConfig when you create a resource. The trainer and generator always run on the same GPU type. Check the model’s row in the catalog for the training modes available on B200.

Request a model

To request a model or config that isn’t in the catalog, contact your Together AI account team.