The latest release of Dev Proxy version 0.28 by the .NET team introduces various new features to enhance observability, plugin extensibility, and integration with AI models. A key highlight of this update is the OpenAITelemetryPlugin, which enables developers to track the usage and estimated costs of OpenAI and Azure OpenAI language model requests in their applications.

This plugin captures details such as the model used, token counts (prompt, completion, and total), per-request cost estimates, and grouped summaries per model. It offers deeper insights into how applications interact with LLMs, allowing visualization of usage patterns and optimization of AI-related expenses using external tools like OpenLIT.

The release also includes support for Microsoft’s Foundry Local, a local AI runtime stack introduced at the recent Build conference. Foundry Local allows developers to redirect cloud-based LLM calls to local environments, reducing costs and enabling offline development.

Dev Proxy can now be configured to utilize local models, with plans to integrate with Foundry Local by default in future versions. Developers can specify the local model and endpoint in the proxy’s configuration file under the languageModel section, offering a cost-effective option for working with LLMs during local development.

For .NET Aspire users, a preview version of Dev Proxy extensions is now accessible. These extensions simplify integration with Aspire applications, enabling Dev Proxy to run locally or via Docker with minimal setup. This enhancement enhances portability and streamlines configuration for distributed development teams.

Additionally, the release expands support for OpenAI payloads beyond text completions, making Dev Proxy compatible with a wider range of completion types. The TypeSpec generation has also been improved to support PATCH operation generation using MergePatchUpdate for clear merge patch behavior.

Dev Proxy now supports JSONC (JSON with comments) in all configuration files, allowing developers to include inline documentation and annotations for improved team collaboration and long-term maintenance. Concurrency improvements in logging and mocking have been implemented to accurately group logs for parallel requests, aiding developers in tracing request behavior effectively.

Two breaking changes are introduced in this release, including the removal of the GraphConnectorNotificationPlugin due to the deprecation of Graph connector deployment via Microsoft Teams. Additionally, the --audience flag in the devproxy jwt create command has been renamed to --audiences, with the shorthand alias -a remaining unchanged.

The CRUD API plugin now features improved CORS handling and consistent JSON responses, enhancing reliability in client-side applications. Lastly, the Dev Proxy Toolkit for Visual Studio Code has been updated to version 0.24.0, introducing new snippets and commands, improved compatibility with Dev Proxy Beta, and enhanced process detection.

For a detailed overview of features, changes, and guidance for this version, interested readers can refer to the full release notes available in the official repository.