Go UUID Generator

Generating UUIDs in Go

• uuid.New() returns a random v4 uuid.UUID — a fixed [16]byte array, so it is comparable, copyable and has no heap allocation as a value. uuid.NewV7() (package v1.6.0 and later) returns a time-ordered v7 value together with an error, because the timestamp source can fail. uuid.UUID.String() renders the canonical hyphenated form.
• For a Go service the interesting decision is which one to use in the schema. A random v4 key is fine as a unique identifier but hostile to a B-tree when rows arrive continuously; a v7 key sorts by creation time, so inserts append. Many Go teams keep both: v7 for the primary key, v4 for anything that must look unpredictable.

How to generate

1. Press Generate UUID above to mint a value in this browser — nothing is sent anywhere.
2. Copy one value with Copy, or set How many and use Copy all for a fixture list.
3. Switch Version if your code needs v7 instead of the v4 default, and turn on Formatting to match your stack's conventions.

Use Cases

• Distributed service keys — minted in the application, so no round trip to the database is needed to learn the ID.
• Request and trace IDs in middleware, propagated through context.
• Idempotency keys for message handlers where redelivery is normal.

How Go UUID Generator Compares

Code Examples

package main

import (
	"fmt"

	"github.com/google/uuid"
)

func main() {
	v4 := uuid.New()                 // random
	v7, err := uuid.NewV7()          // time-ordered
	if err != nil {
		panic(err)
	}

	fmt.Println(v4.String())         // 4de2b1c0-8a7f-4e31-9c2d-1f0a6b7c8d9e
	fmt.Println(v7.String())         // 0198c2f1-6d8a-7cc3-9b21-4a7f0e5d3c11
}

id, err := uuid.Parse("4de2b1c0-8a7f-4e31-9c2d-1f0a6b7c8d9e")
if err != nil {
	// malformed input
}

// Optional column value
nullable := uuid.NullUUID{UUID: id, Valid: true}

Frequently Asked Questions

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