Go quickstart — 5 lines to ship

Go developers can use the official sashabaranov/go-openai SDK against VerticalAPI by setting BaseURL and adding the provider key as a custom header. Suitable for high-throughput backends.

5-step setup

From zero to first call

Sign up at verticalapi.com/dashboard

Free tier — no card required. Generates your vapi_ key automatically.
Add a provider key

Paste your OpenAI sk-..., Anthropic sk-ant-..., or Google AIza... into the dashboard. Encrypted at rest.
Install the Go SDK

go get github.com/sashabaranov/go-openai
Run the example below

Drop-in OpenAI SDK pattern — base_url + api_key + provider key header. That's it.
Inspect the trace

Every call gets a unique request ID. Find it in the dashboard with full latency, tokens, and cost breakdown.

Working example

Go — first call

quickstart.goGo
package main

import (
    "context"
    "fmt"
    "net/http"
    openai "github.com/sashabaranov/go-openai"
)

func main() {
    cfg := openai.DefaultConfig("vapi_...")
    cfg.BaseURL = "https://api.verticalapi.com/v1"
    cfg.HTTPClient = &http.Client{
        Transport: &headerTransport{
            base: http.DefaultTransport,
            providerKey: "sk-...",
        },
    }
    client := openai.NewClientWithConfig(cfg)

    resp, _ := client.CreateChatCompletion(context.Background(), openai.ChatCompletionRequest{
        Model: "gpt-4o",
        Messages: []openai.ChatCompletionMessage{
            {Role: "user", Content: "Hello, world"},
        },
    })
    fmt.Println(resp.Choices[0].Message.Content)
}

type headerTransport struct{ base http.RoundTripper; providerKey string }
func (h *headerTransport) RoundTrip(r *http.Request) (*http.Response, error) {
    r.Header.Set("X-Provider-Key", h.providerKey)
    return h.base.RoundTrip(r)
}

Swap model for claude-sonnet-4-5, gemini-2.5-pro, or any of 25+ supported providers. Update X-Provider-Key to match.

Troubleshooting