VoyageAI.NET

Typed .NET client for the Voyage AI API

Text embeddings, multimodal embeddings, and reranking. Source-generated JSON, auto-batching, and built-in resilience — zero configuration.

---

Wraps the Voyage AI REST API end-to-end with a battle-tested HTTP stack: typed HttpClient via IHttpClientFactory, HTTP/2 with ALPN, automatic decompression, pooled connections with DNS refresh, source-generated JSON (AOT- and trim-safe), streaming batch operations via IAsyncEnumerable, and automatic retry / circuit breaker / timeout via Microsoft.Extensions.Http.Resilience.

thousands of texts  ──>  EmbedBatchAsync  ──>  IAsyncEnumerable<EmbeddingResponse>
                         auto-batched                streamed in order
                         8x parallel                 resilient (retry + CB)

Install

dotnet add package VoyageAI.NET

30-second Example

// Registration
builder.Services.AddVoyageClient(options =>
{
    options.ApiKey = builder.Configuration["Voyage:ApiKey"]!;
});

// Injection
public class SearchService(IVoyageClient voyage)
{
    public async Task<float[]> EmbedAsync(string text, CancellationToken ct)
    {
        var response = await voyage.EmbedAsync(text, VoyageModels.Voyage4, InputType.Query, ct);
        return response.Data[0].Embedding;
    }
}

Without DI:

var http = new HttpClient
{
    BaseAddress = new Uri("https://api.voyageai.com/v1/"),
    DefaultRequestHeaders = { Authorization = new AuthenticationHeaderValue("Bearer", apiKey) }
};

var client = new VoyageClient(http);

Text Embeddings

// Single
var r = await client.EmbedAsync("hello world", VoyageModels.Voyage4, InputType.Query);

// Multiple
var r = await client.EmbedAsync(["hello", "world"], VoyageModels.Voyage4);

// Full control
var r = await client.EmbedAsync(new EmbeddingRequest
{
    Input = "hello world",                  // string or string[]
    Model = VoyageModels.Voyage4,           // required
    InputType = InputType.Query,            // "query" or "document" (optional)
    OutputDimension = 512,                  // 256, 512, 1024, 2048 (optional)
    OutputDtype = "float",                  // "float", "int8", "uint8", "binary", "ubinary"
    EncodingFormat = "base64",              // null or "base64" (optional)
    Truncation = true                       // default: true
});

// r.Data[0].Embedding  → float[]
// r.Usage.TotalTokens  → int

Batch Embeddings

Embed thousands of texts with automatic batching and concurrency control. Results stream via IAsyncEnumerable as each batch completes, preserving input order.

var all = new List<float[]>();

await foreach (var r in client.EmbedBatchAsync(
    thousandsOfTexts,
    VoyageModels.Voyage4,
    inputType: InputType.Document,
    batchSize: 128,        // max per request (default: 128)
    maxConcurrency: 8))    // parallel requests (default: 8)
{
    foreach (var item in r.Data)
        all.Add(item.Embedding);
}

Multimodal Embeddings

var r = await client.EmbedMultimodalAsync(new MultimodalEmbeddingRequest
{
    Inputs =
    [
        new MultimodalInput
        {
            Content =
            [
                new TextContentPart { Text = "A photo of a cat" },
                new ImageUrlContentPart { ImageUrl = "https://example.com/cat.jpg" },
                // or: new ImageBase64ContentPart { ImageBase64 = "..." }
            ]
        }
    ],
    Model = VoyageModels.VoyageMultimodal35,
    InputType = InputType.Document
});

// r.Data[0].Embedding    → float[]
// r.Usage.TextTokens     → int
// r.Usage.ImagePixels    → int
// r.Usage.TotalTokens    → int

// Batch — same pattern as text
await foreach (var r in client.EmbedMultimodalBatchAsync(
    inputs, VoyageModels.VoyageMultimodal35, batchSize: 32, maxConcurrency: 4))
{
    // process
}

Reranking

// Simple
var r = await client.RerankAsync(
    "When is Apple's conference call scheduled?",
    documents,
    VoyageModels.Rerank25,
    topK: 3);

// Full control
var r = await client.RerankAsync(new RerankRequest
{
    Query = "When is Apple's conference call scheduled?",
    Documents =
    [
        "The Mediterranean diet emphasizes fish, olive oil, and vegetables...",
        "Apple's conference call is scheduled for Thursday, November 2, 2023...",
        "Shakespeare's works endure in literature..."
    ],
    Model = VoyageModels.Rerank25,
    TopK = 3,
    ReturnDocuments = true,
    Truncation = true
});

// r.Data[0].Index           → int (original position)
// r.Data[0].RelevanceScore  → double
// r.Data[0].Document        → string? (if ReturnDocuments = true)
// r.Usage.TotalTokens       → int

Models

Use VoyageModels.* constants — no magic strings.

Embedding

Constant	API id
VoyageModels.Voyage4Large	voyage-4-large
VoyageModels.Voyage4	voyage-4
VoyageModels.Voyage4Lite	voyage-4-lite
VoyageModels.VoyageCode3	voyage-code-3
VoyageModels.VoyageFinance2	voyage-finance-2
VoyageModels.VoyageLaw2	voyage-law-2
VoyageModels.VoyageCode2	voyage-code-2

Multimodal

Constant	API id
VoyageModels.VoyageMultimodal35	voyage-multimodal-3.5

Rerank

Constant	API id
VoyageModels.Rerank25	rerank-2.5
VoyageModels.Rerank25Lite	rerank-2.5-lite

Error Handling

API errors throw VoyageApiException:

try
{
    var r = await client.EmbedAsync(request);
}
catch (VoyageApiException ex)
{
    Console.WriteLine(ex.StatusCode);  // e.g., 400
    Console.WriteLine(ex.Detail);      // e.g., "Invalid model name"
}

HTTP Stack & Resilience

AddVoyageClient configures a production-ready HTTP stack out of the box:

• HTTP/2 via ALPN (HttpVersionPolicy.RequestVersionOrHigher) with graceful HTTP/1.1 fallback
• SocketsHttpHandler with PooledConnectionLifetime = 5min and PooledConnectionIdleTimeout = 2min — refreshes DNS without killing in-flight requests
• AutomaticDecompression = All (gzip, brotli, deflate)
• EnableMultipleHttp2Connections to avoid HTTP/2 stream-concurrency limits under load
• Standard resilience via Microsoft.Extensions.Http.Resilience: exponential-backoff retry on 429/5xx, circuit breaker, request timeout
• AOT- and trim-safe: source-generated System.Text.Json, zero reflection, IsAotCompatible=true

Configuration

builder.Services.AddVoyageClient(options =>
{
    options.ApiKey = "your-api-key";
    options.BaseUrl = new Uri("https://api.voyageai.com/v1/");  // default
});

Supported Frameworks

net8.0 · net9.0 · net10.0

Project Layout

src/VoyageAI.NET/
  Client/           VoyageClient partials (core, Embeddings, Multimodal, Rerank)
  Models/           Request/response records (immutable, `required init`)
  Extensions/       AddVoyageClient DI extension
  Constants/        VoyageModels, InputType
  Infrastructure/   VoyageJsonContext (source-gen), VoyageApiException, options

Samples

Runnable console sample in samples/VoyageAI.NET.Sample:

export VOYAGE_API_KEY=your-key
dotnet run --project samples/VoyageAI.NET.Sample

Build & Test

dotnet build
dotnet test

License

MIT. Built by Outmatic.