Dev Proxy v1.3.0: HAR File Generation, LLM Usage Tracking, and Enhanced API Testing Feature

Write for InfoQ

The Microsoft 365 Developer team has announced the release of Dev Proxy v1.3.0, introducing several new features aimed at improving debugging, testing, and API monitoring. The update includes two new plugins, HAR file generation for standardized network tracing and OpenAI usage tracking for better visibility into AI-related costs, along with enhancements to permissions analysis, OpenAPI specification generation, and overall stability.

According to the announcement, the new HarGeneratorPlugin enables automatic creation of HTTP Archive (HAR) files from intercepted API requests and responses. HAR files are widely recognized as an industry standard for capturing and sharing network activity. This addition allows developers to export reproducible network traces that can be analyzed in tools like Chrome DevTools and Fiddler.

The plugin aims to simplify collaboration among development, QA, and support teams by providing a universal debugging format compatible across platforms. As noted in the release, the feature ensures "complete network activity logs" can be generated and shared without vendor lock-in, simplifying troubleshooting and performance analysis.

(Screenshot Source: Official Microsoft 365 Developer blog)

Another major addition is the OpenAIUsageDebuggingPlugin, designed for developers building AI-driven applications. This plugin records detailed OpenAI API usage data, including token consumption, model calls, and request statistics, into CSV files.

As reported, it allows developers to monitor and analyze how their applications use large language models, helping them detect inefficient usage patterns and manage costs during development and testing. The team emphasized that this feature helps identify potential issues "before they become expensive surprises in production."

The release also introduces improvements to the OpenAPI specification generation process, particularly for multi-port and multi-service scenarios. In earlier versions, API specification files could overwrite each other when tests involved multiple services running on different ports.

The updated OpenApiSpecGeneratorPlugin now includes port information in filenames and intelligently aggregates service calls, ensuring no data loss during complex integration testing. This enhancement is especially relevant for teams working with microservices or dynamic testing environments.

Additionally, the minimal permissions plugins now include support for specifying authentication schemes, providing finer control when analyzing APIs that use multiple authentication methods.

The update extends several plugins, including the MinimalPermissionsPlugin, ApiCenterMinimalPermissionsPlugin, and MinimalPermissionsGuidancePlugin, with new configuration options that allow developers to define which authentication scheme is being used. This ensures more accurate permission evaluation across varied authentication contexts, such as application versus delegated permissions.

Alongside Dev Proxy v1.3.0, the Dev Proxy Toolkit for Visual Studio Code has been updated to version 1.8.0. The toolkit now includes updated JSON snippets aligned with the new schema, as well as snippets for the HarGeneratorPlugin and OpenAIUsageDebuggingPlugin, enabling developers to integrate the new functionality directly within their development environment.

Other changes in this release include improved CSV logging for API activity tracking, general bug fixes, and performance optimizations.

For interested readers, full release notes and documentation are available on the official Dev Proxy GitHub repository and Microsoft 365 Developer blog.

Related Topics:

• Development
• .NET 8
• .NET
• .NET 9
• .NET Core
• .NET 10

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