ChromaDotNet.Client

Install

For Microsoft.Extensions.DependencyInjection, with AddChromaClient, AddKeyedChromaClient and CreateChromaClient:

The packages are named ChromaDotNet.*. The namespaces keep their original names, such as ChromaDB.Client.

Example

Start Chroma, for example with Docker:

Then add two records with their embeddings and query the nearest one:

using ChromaDB.Client;
using ChromaDB.Client.Models;

using var client = new ChromaClient("http://localhost:8000");
var collection = await client.GetOrCreateCollectionAsync("fruits");
var fruits = client.GetCollectionClient(collection);

await fruits.AddAsync(["apple", "lemon"],
    embeddings: [new([1f, 0f, 0f]), new([0f, 1f, 0f])],
    documents: ["A crunchy apple", "A sour lemon"]);

var results = await fruits.QueryAsync(new ReadOnlyMemory<float>([0f, 0.9f, 0.1f]),
    nResults: 1, include: ChromaQueryInclude.Documents | ChromaQueryInclude.Distances);

foreach (var result in results)
    Console.WriteLine($"{result.Id}: {result.Document} ({result.Distance})");

Tested on 25 October 2026 with ChromaDotNet.Client 2.18.0 on Chroma 1.5.9.

Try it in your browser: a GitHub Codespace with .NET and Chroma, then dotnet run Samples/quickstart.cs.

Documentation

• Connecting: the URI, the HttpClient, threads, the API version, authentication and connection strings.
• Dependency injection: AddChromaClient and AddKeyedChromaClient.
• Collections: collections, tenants and databases, collections by id.
• Records: URIs, large writes, deletes and base64 embeddings.
• Embeddings: embeddings from an IEmbeddingGenerator, query texts and the default embedding function of Chroma.
• Metadata values: values, lists, deletions in updates and upserts, document copies, conversions.
• Queries and filters: queries, GetAsync in pages, where and document filters.
• Upsert strategies: Server and SkipUnchangedEmbeddings.
• Index settings: the distance, the HNSW and SPANN settings, ModifyConfigurationAsync.
• Errors: ChromaException and CollectionExistsAsync.
• Mocks in tests: mocking ChromaClient and ChromaCollectionClient.
• Health, traces and metrics: HealthcheckAsync and OpenTelemetry.
• Chroma Cloud: options, identity, batches, quotas and the operations of Chroma Cloud.
• Search: the Search API and hybrid search with BM25.
• Sparse vectors and schema: sparse vectors, BM25 indexes and the indexes of a schema.
• Platforms: the builds, trimming and NativeAOT.

The compatibility table shows every check of the latest release on Chroma 1.5.9 and on Chroma Cloud, on each .NET runtime and platform.