Claude API in Go: Building High-Performance AI Services

Why Go for Claude?

Go goroutines handle concurrent AI requests efficiently. Static typing catches integration errors at compile time. Performance means the API layer never becomes the bottleneck. The official Anthropic Go SDK was released in late 2025.

go get github.com/anthropics/anthropic-sdk-go

Basic Usage

package main

import (
    "context"
    "fmt"
    "os"
    anthropic "github.com/anthropics/anthropic-sdk-go"
    "github.com/anthropics/anthropic-sdk-go/option"
)

func main() {
    client := anthropic.NewClient(option.WithAPIKey(os.Getenv("ANTHROPIC_API_KEY")))
    msg, err := client.Messages.New(context.Background(),
        anthropic.MessageNewParams{
            Model:     anthropic.F(anthropic.ModelClaude_Sonnet_4_6),
            MaxTokens: anthropic.F(int64(1024)),
            Messages: anthropic.F([]anthropic.MessageParam{
                anthropic.UserMessageParam(anthropic.NewTextBlock("Hello")),
            }),
        })
    if err != nil { fmt.Fprintln(os.Stderr, err); os.Exit(1) }
    if tb, ok := msg.Content[0].(anthropic.TextBlock); ok {
        fmt.Println(tb.Text)
    }
}

Concurrent Batch Processing

Use goroutines with a semaphore from golang.org/x/sync/semaphore to process multiple prompts concurrently while respecting rate limits. Set the semaphore weight to 10 for 10 concurrent requests.

Retry Logic

Handle status 429 (rate limit), 500, and 529 (overloaded) with exponential backoff using context cancellation. Do not retry status 400 (bad request) or 401 (auth error) -- these require code changes.

Production HTTP Service

Use the standard net/http package with a handler that decodes the request, calls Claude with retry logic, and returns JSON. Include token usage in the response for cost tracking. The Go standard library handles concurrency and connection pooling without additional dependencies.