> This page is for version v1.1.1.
> For other versions, use one of these documentation indexes:
> - Latest (v1.5.1) (default): https://docs.nvidia.com/dynamo/latest/llms.txt
> - dev: https://docs.nvidia.com/dynamo/dev/llms.txt
> - v1.5.1: https://docs.nvidia.com/dynamo/v1.5.1/llms.txt
> - v1.5.0: https://docs.nvidia.com/dynamo/v1.5.0/llms.txt
> - v1.4.2: https://docs.nvidia.com/dynamo/v1.4.2/llms.txt
> - v1.4.1: https://docs.nvidia.com/dynamo/v1.4.1/llms.txt
> - v1.4.0: https://docs.nvidia.com/dynamo/v1.4.0/llms.txt
> - v1.3.0: https://docs.nvidia.com/dynamo/v1.3.0/llms.txt
> - v1.2.1: https://docs.nvidia.com/dynamo/v1.2.1/llms.txt
> - v1.2.0: https://docs.nvidia.com/dynamo/v1.2.0/llms.txt
> - v1.1.1: https://docs.nvidia.com/dynamo/v1.1.1/llms.txt
> - v1.1.0: https://docs.nvidia.com/dynamo/v1.1.0/llms.txt
> - v1.0.2: https://docs.nvidia.com/dynamo/v1.0.2/llms.txt
> - v1.0.1: https://docs.nvidia.com/dynamo/v1.0.1/llms.txt
> - v1.0.0: https://docs.nvidia.com/dynamo/v1.0.0/llms.txt
> - v0.9.1: https://docs.nvidia.com/dynamo/v-0-9-1/llms.txt
> - v0.9.0: https://docs.nvidia.com/dynamo/v-0-9-0/llms.txt
> - v0.8.1: https://docs.nvidia.com/dynamo/v-0-8-1/llms.txt
> - v0.8.0: https://docs.nvidia.com/dynamo/v-0-8-0/llms.txt
> - v0.7.1: https://docs.nvidia.com/dynamo/v-0-7-1/llms.txt
> - v0.7.0: https://docs.nvidia.com/dynamo/v-0-7-0/llms.txt

> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://docs.nvidia.com/dynamo/llms.txt. For full content including API reference and SDK examples, see https://docs.nvidia.com/dynamo/llms-full.txt.

# Reasoning

Some models emit reasoning or thinking content separately from their final
response. Dynamo can split that output into `reasoning_content` and normal
assistant content by configuring a reasoning parser. As with tool calling,
there are two ways to do this to ensure wide coverage and day0 model support.

## Choose a parsing path

| Path | When to use | Page |
|------|-------------|------|
| **Dynamo** | Dynamo ships a Rust parser for the model's reasoning format. Lowest latency, the default path. | [Reasoning Parsing (Dynamo)](/dynamo/v1.1.1/user-guides/reasoning/reasoning-parsing-dynamo) |
| **Engine Fallback** | Use the framework's implementation (vLLM or SGLang) for pre/post processing, including tool call and reasoning parsing - ensure consistency with framework behavior. | [Reasoning Parsing (Engine Fallback)](/dynamo/v1.1.1/user-guides/reasoning/reasoning-parsing-engine-fallback) |

Start with the Dynamo path. Fall back to the engine path only when Dynamo's
registry does not list a parser for your model.

## See Also

- [Tool Calling](/dynamo/v1.1.1/user-guides/tool-calling) -- parse tool calls out of model
  output. Several models need both a reasoning parser and a tool-call parser
  configured together.
- [Frontend Configuration Reference](../components/frontend/configuration.md) --
  full CLI flag reference.