Go Email Verification SDK — Verify Emails in Go

Install the Go email verification SDK by running go get github.com/ecomtechbd/ev-go in your module directory. The package requires Go 1.18 or higher and has zero external dependencies, relying entirely on the Go standard library for HTTP communication, JSON parsing, and cryptographic operations. The module follows semantic versioning and is available through the Go module proxy for fast, reliable downloads.

After installation, create a new client using ev.NewClient() with your API key. You can also set the EV_API_KEY environment variable and call ev.NewClientFromEnv() for automatic key resolution. The client constructor accepts functional options for configuring timeout, maximum retries, sandbox mode, a custom HTTP client, and a custom base URL. The resulting client is safe for concurrent use across multiple goroutines and internally manages connection pooling via Go's http.Transport. All verification methods accept a context.Context as their first parameter, supporting timeout, cancellation, and deadline propagation throughout your application.

The Go SDK follows idiomatic Go error handling by returning errors as the second return value from all methods. Specific error types can be checked using the errors.Is() and errors.As() functions. The SDK defines sentinel errors including ev.ErrAuthentication, ev.ErrRateLimit, ev.ErrValidation, and ev.ErrNetwork. The RateLimitError type provides a RetryAfter field of type time.Duration indicating how long to wait before retrying.

The SDK automatically retries transient errors with exponential backoff, including 429 rate limit responses and 5xx server errors. Configure retry behavior with ev.WithMaxRetries() and ev.WithRetryDelay() options. Context cancellation is respected at all stages, so a cancelled context immediately stops retries. For batch operations, per-email errors are captured in each result's Error field rather than failing the entire batch. Use client.RateLimitRemaining() to check your remaining quota. Wrap the error check in a helper function for cleaner code in handlers that verify many emails.

package main

import (
    "context"
    "errors"
    "fmt"
    "log"
    "time"

    ev "github.com/ecomtechbd/ev-go"
)

func main() {
    client := ev.NewClient("YOUR_API_KEY", ev.WithMaxRetries(3))
    ctx := context.Background()

    result, err := client.Verify(ctx, "user@example.com")
    if err != nil {
        var rateLimitErr *ev.RateLimitError
        if errors.As(err, &rateLimitErr) {
            fmt.Printf("Rate limited. Retry after %v\n", rateLimitErr.RetryAfter)
            time.Sleep(rateLimitErr.RetryAfter)
        } else if errors.Is(err, ev.ErrAuthentication) {
            log.Fatal("Invalid API key. Check EV_API_KEY.")
        } else if errors.Is(err, ev.ErrValidation) {
            fmt.Println("Invalid email format:", err)
        } else {
            log.Fatal("Verification failed:", err)
        }
        return
    }

    fmt.Printf("Status: %s, Score: %d\n", result.Status, result.Score)
}