Skip to content
Util.Ninja

GUID / UUID Generator

Generate a new GUID (also called a UUID) with one click and copy it to the clipboard. The standard UUID button creates a random version 4 UUID using your browser’s secure random number generator; the other buttons show COMB, sequential, MAC-based and custom GUID styles.

GUID stands for Globally Unique Identifier. It is a 128-bit identifier used in software development and various other fields to uniquely identify objects, entities, or resources. GUIDs are generated according to specific algorithms, ensuring that each generated identifier is highly unlikely to be duplicated. GUIDs are represented as 32 hexadecimal digits grouped into five sections as 8-4-4-4-12, separated by hyphens XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX for example, "8d37ee21-7839-4e1d-a8f3-ebc027277b98". They are commonly used in databases, distributed systems, and various programming languages to create unique identifiers for different purposes, such as database records, files, or components in a software system.

GUID types: generate the one you need

1. UUID version 4 (random, recommended)

UUID is a widely used type of GUID that follows a standardized format specified by RFC 4122. It is generated using a combination of timestamp, random numbers, and other unique identifiers. UUIDs are globally unique and have a low probability of collision.

Generate UUID
UUID

2. COMB GUID (Combination GUID):

COMB GUID is a type of GUID specifically designed for use in databases to minimize index fragmentation. It combines a timestamp with a random or sequential number to create a unique identifier. COMB GUIDs are often used in database systems to generate primary keys for records.

Generate COMB GUID
COMB GUID

3. Sequential GUID:

Sequential GUID is generated in a sequential order to ensure that newly generated GUIDs are approximately ordered by time. This can be useful for certain applications where ordering by creation time is important. However, sequential GUIDs may lead to contention in distributed systems.

Generate Seq GUID
Sequential GUID

4. MAC Address-based GUID:

MAC Address-based GUIDs are generated using the unique MAC address of a network interface card (NIC) combined with additional data to create a globally unique identifier. These GUIDs are highly unique but may pose privacy concerns as they may reveal information about the device's hardware.

Generate MAC GUID
MAC GUID

5. Custom GUIDs:

Custom GUIDs are generated using custom algorithms or specific data sources to create unique identifiers tailored to a particular application or use case. These GUIDs may vary significantly in their generation method and uniqueness characteristics based on the specific requirements of the application.

Generate Cust GUID
Custom GUID

How to use

  1. Choose the GUID type you need above; most people want the standard UUID.
  2. Press its Generate button to create a new value.
  3. Press the copy icon next to it to copy the GUID to your clipboard.

Frequently asked questions

What is the difference between a GUID and a UUID?

They are the same thing. UUID (Universally Unique Identifier) is the name used in the RFC standard, while GUID (Globally Unique Identifier) is the name Microsoft uses. Both are 128-bit values written as 32 hexadecimal digits in the 8-4-4-4-12 format.

Can two UUIDs ever be the same?

In theory yes, in practice no. A random version 4 UUID has 122 random bits, so you would need to generate billions of them every second for many years before a duplicate became likely.

Which GUID type should I use for database keys?

Random v4 UUIDs are the safe default. If insert performance on a clustered index matters, a time-ordered type such as a COMB or sequential GUID keeps new rows close together and reduces index fragmentation.

Are these GUIDs generated on a server?

No. They are created in your browser with JavaScript, nothing is sent to a server.

GUIDs (Globally Unique Identifiers) are important for several reasons:

  1. Uniqueness: GUIDs are designed to be globally unique, meaning the probability of generating the same identifier twice is extremely low. This makes them invaluable for ensuring the uniqueness of entities, objects, or resources in distributed systems where multiple entities may need to generate identifiers independently.
  2. Scalability: GUIDs allow systems to scale horizontally without the risk of identifier collisions. In large-scale distributed systems, where multiple nodes generate identifiers concurrently, the use of GUIDs ensures that each entity can independently generate unique identifiers without coordination with other nodes.
  3. Persistence: GUIDs remain unique even across different systems and over time. This persistence is valuable in scenarios where data needs to be replicated or migrated between systems without losing its identity or integrity.
  4. Security: GUIDs can be used as security tokens or session identifiers, providing a high level of security against unauthorized access or tampering. When combined with encryption and other security measures, GUIDs help protect sensitive data and prevent unauthorized access to resources.
  5. Referential Integrity: GUIDs are commonly used as primary keys in databases, ensuring referential integrity and facilitating efficient data retrieval and manipulation. By using GUIDs as primary keys, systems can avoid conflicts and inconsistencies when merging or synchronizing data from different sources.
  6. Cross-platform Compatibility: GUIDs are platform-independent and can be generated and interpreted across different systems and programming languages. This interoperability makes them suitable for use in heterogeneous environments where interoperability between systems is essential.
  7. Identification and Tracking: GUIDs enable the unique identification and tracking of entities, transactions, or events across distributed systems. This is particularly useful in scenarios such as auditing, logging, or tracking the lineage of data in complex workflows.