# Microsoft .NET

> Microsoft .NET is a free, cross-platform, open-source developer platform. Its one public, callable
> HTTP API is the NuGet Server API (V3) at https://api.nuget.org/v3 — anonymous for all reads,
> API-key authenticated for publishing. The other .NET surfaces in this profile (the API Browser,
> the dotnet CLI, ASP.NET Core, .NET Aspire) are documentation, tooling and frameworks rather than
> callable web APIs. Generated by API Evangelist from apis.yml and this repository's artifacts;
> Microsoft does not publish an llms.txt on any .NET host (probed 2026-08-29, all 404).

## Start here

- [NuGet V3 service index](https://api.nuget.org/v3/index.json): The entry point. Do not hardcode resource URLs — read resources[] and match on @type.
- [NuGet Server API overview](https://learn.microsoft.com/en-us/nuget/api/overview): The protocol specification.
- [.NET documentation](https://learn.microsoft.com/en-us/dotnet/): Platform documentation root.
- [.NET API Browser](https://learn.microsoft.com/en-us/dotnet/api/): Class-library reference across .NET 10, .NET Standard and .NET Framework.

## APIs

- [NuGet Service Index API](openapi/microsoft-net-serviceindex-api-openapi.yml): getServiceIndex — GET /index.json.
- [NuGet Search API](openapi/microsoft-net-search-api-openapi.yml): searchPackages — GET /query with q, skip, take, prerelease, semVerLevel, packageType.
- [NuGet Registration API](openapi/microsoft-net-registration-api-openapi.yml): getRegistrationIndex, getRegistrationLeaf — package metadata. IDs must be lowercased.
- [NuGet Package Content API](openapi/microsoft-net-packagecontent-api-openapi.yml): listPackageVersions, downloadPackage, downloadNuspec — the flat container.

## Agent surfaces

- [MCP servers](mcp/microsoft-net-mcp.yml): Two first-party Microsoft servers. The Microsoft Learn Docs MCP server is REMOTE and anonymous at https://learn.microsoft.com/api/mcp (microsoft_docs_search, microsoft_code_sample_search, microsoft_docs_fetch). The NuGet MCP server is LOCAL-STDIO only — `dnx NuGet.Mcp.Server --yes`, requires a .NET 10 SDK on the machine first.
- [Tool crosswalk](mcp/microsoft-net-tool-crosswalk.yml): The MCP and REST surfaces do not overlap; all 7 REST operations are rest_only.
- [Agent skills](skills/_index.yml): Packaged operating instructions grounded in real operationIds.
- No A2A agent card is served on any Microsoft .NET host (probed 2026-08-29).

## Contracts and conventions

- [Authentication](authentication/microsoft-net-authentication.yml): X-NuGet-ApiKey header, write operations only. All reads are anonymous.
- [Conventions](conventions/microsoft-net-conventions.yml): Service-index discovery, lowercased IDs, offset pagination, two-layer versioning, reversibility.
- [Errors](errors/microsoft-net-problem-types.yml): Not RFC 9457. Two envelopes — a V3 JSON {statusCode,message} and a V2 OData XML m:error.
- [Rate limits](rate-limits/microsoft-net-rate-limits.yml): Published per-endpoint IP and API-key limits. No RateLimit-* response headers; the wait is prose inside the body.
- [Lifecycle](lifecycle/microsoft-net-lifecycle.yml): Annual November majors, LTS 3 years / STS 2 years. V2 OData custom queries deprecated 2021-03-09 (HTTP 400, code NuGet.V2.Deprecated).
- [Conformance](conformance/microsoft-net-conformance.yml): OData v2 ($metadata CSDL published), NuGet V3 protocol, SemVer 2.0.0, RFC 9116.
- [Data model](data-model/microsoft-net-data-model.yml): Hypermedia-linked; the natural key is (id, version).

## Before you write

- nuget.org does NOT support permanent package deletion. A push is effectively permanent.
- DELETE on the publish endpoint is an UNLIST, not a delete. It is reversible with POST on the same URL (relist).
- Pushing a package ID and version that already exists returns HTTP 409. There is no idempotency key.
- Rehearse against the separate pre-production gallery: https://apiint.nugettest.org/v3/index.json (see sandbox/microsoft-net-sandbox.yml). Production and test API keys look identical — the --source argument is the entire safety boundary.

## Packages

- [First-party packages](packages/microsoft-net-packages.yml): 21 first-party NuGet packages with versions and publish dates. No first-party client library exists on npm, PyPI, RubyGems, Packagist, crates.io, Maven Central or pkg.go.dev.

## Operations

- [Status](https://status.nuget.org/)
- [Release notes](https://github.com/dotnet/core/blob/main/release-notes/README.md) and the machine-readable [releases index](https://raw.githubusercontent.com/dotnet/core/main/release-notes/releases-index.json)
- [Support policy](https://dotnet.microsoft.com/en-us/platform/support/policy/dotnet-core)
- [Breaking changes](https://learn.microsoft.com/en-us/dotnet/core/compatibility/)
- [Roadmap](https://github.com/dotnet/core/blob/main/roadmap.md)
- [Security disclosure](https://www.microsoft.com/.well-known/security.txt) via MSRC
- [GitHub organization](https://github.com/dotnet)
- [Blog](https://devblogs.microsoft.com/dotnet/)