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TypeChat is a library that makes it easy to build natural language interfaces using types.

Building natural language interfaces has traditionally been difficult. These apps often relied on complex decision trees to determine intent and collect the required inputs to take action. Large language models (LLMs) have made this easier by enabling us to take natural language input from a user and match to intent. This has introduced its own challenges including the need to constrain the model's reply for safety, structure responses from the model for further processing, and ensuring that the reply from the model is valid. Prompt engineering aims to solve these problems, but comes with a steep learning curve and increased fragility as the prompt increases in size.

TypeChat replaces prompt engineering with schema engineering.

Simply define types that represent the intents supported in your natural language application. That could be as simple as an interface for categorizing sentiment or more complex examples like types for a shopping cart or music application. For example, to add additional intents to a schema, a developer can add additional types into a discriminated union. To make schemas hierarchical, a developer can use a "meta-schema" to choose one or more sub-schemas based on user input.

After defining your types, TypeChat takes care of the rest by:

1. Constructing a prompt to the LLM using types.
2. Validating the LLM response conforms to the schema. If the validation fails, repair the non-conforming output through further language model interaction.
3. Summarizing succinctly (without use of a LLM) the instance and confirm that it aligns with user intent.

Types are all you need!

The TypeScript/JavaScript package requires Node.js 24.22.1 or newer. Development uses Node.js 24.22.1, pinned in .nvmrc, which includes the October 21, 2026 security fixes.

Install TypeChat for TypeScript/JavaScript:

npm install typechat

You can also work with TypeChat from source for:

• Python
• TypeScript
• C#/.NET

To see TypeChat in action, we recommend exploring the TypeChat example projects. You can try them on your local machine or in a GitHub Codespace.

To learn more about TypeChat, visit the documentation which includes more information on TypeChat and how to get started.

GOALS.md defines what belongs in TypeChat, what does not, and what is still under consideration. It is the primary repository policy for product scope. Changes require explicit approval from the human project owner, @robgruen; community interest and AI recommendations do not change it. Read it before proposing a new direction. Ordinary in-scope maintenance follows the normal contribution process.

We are experimenting with a gradual transition to a semi-automated repository. The initial agent-assisted workflow keeps humans in the loop, while our longer-term goal is to help community proposals progress from discussion to accepted, reviewed changes with less manual coordination. Read about the automation experiment and how to participate.

Status as of 2026-10-30 (UTC): The latest backlog assessment completed successfully after the control hardening merged through #491. It inventories 20 issues and 13 open PRs. The earlier saved draft inventories 21 open issues and 25 open pull requests at the assessment time, with plain-language next steps and project-direction classifications.

The latest run used 23 model calls and 148.42 of the main assessment's 400 AI credits. Detection used a separate 7.89 credits. Its 216 tool calls stayed within the allowed set; native diagnostics recorded one failure and no repeated requests. Verification remains partial: tests, CI definitions, and job logs were not checked. The earlier CI access restriction was not retested. Reports are not acceptance of work, GitHub Copilot code reviews, or merge approval.

The next owner-approved discussion pilot is prepared for review. It adds /typechat draft and exact-draft publication for Issues and Discussions, with a 50-credit main drafting budget. It is not active until merged and live-verified, and does not enable acceptance or builds.

Implementation dates do not mean a feature is enabled on GitHub. Existing maintenance and deployment workflows are unchanged. See the detailed status and workflow model configuration.

The saved report is a historical snapshot, not today's backlog. Later merges and decisions do not rewrite it or turn its recommendations into project policy.

Start with the project goals and non-goals. Proposals that would change these boundaries need an owner-approved policy change before their implementation can be accepted.

Repository automation experiment: We are experimenting with a gradual transition to a semi-automated repository. The initial agent-assisted workflow keeps humans in the loop, while our longer-term goal is to help community proposals progress from discussion to accepted, reviewed changes with less manual coordination. Read about the automation experiment and how to participate.

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

When you submit a pull request, a CLA bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

The website source is in site. From the repository root:

npm --prefix site ci
npm --prefix site run build
npm --prefix site run serve

For UI changes, check keyboard navigation, including visible focus in Windows high-contrast themes. Focus indicators should have at least 3:1 contrast against the adjacent background. Check reflow at a 320 x 256 CSS-pixel viewport, equivalent to 400% zoom at 1280 x 1024. Also apply text-spacing overrides: line height of 1.5, letter spacing of 0.12em, word spacing of 0.16em, and paragraph spacing of 2em. The install command must remain readable and its copy button visible and keyboard-operable. With JavaScript disabled, the command should remain readable and the inactive copy button should be hidden.

This project may contain trademarks or logos for projects, products, or services. Authorized use of Microsoft trademarks or logos is subject to and must follow Microsoft's Trademark & Brand Guidelines. Use of Microsoft trademarks or logos in modified versions of this project must not cause confusion or imply Microsoft sponsorship. Any use of third-party trademarks or logos are subject to those third-party's policies.