Generate a UUID in Python

The standard library: uuid4

import uuid

id = uuid.uuid4()        # UUID('f47ac10b-58cc-4372-a567-0e02b2c3d479')
str(id)                  # 'f47ac10b-58cc-4372-a567-0e02b2c3d479'
id.hex                   # 'f47ac10b58cc4372a5670e02b2c3d479', no hyphens
id.bytes                 # 16 raw bytes for binary columns
id.int                   # the 128 bit integer

uuid4() returns a UUID object, not a string. That trips people up in JSON: json.dumps({"id": uuid.uuid4()}) raises a TypeError. Convert with str() first, or pass default=str to dumps.

Time ordered v7

Python 3.14 added uuid.uuid7() to the standard library, along with uuid6() and uuid8(). On older versions use a small package.

# Python 3.14+
uuid.uuid7()

# Python 3.8 to 3.13
pip install uuid-utils
import uuid_utils
uuid_utils.uuid7()       # returns a UUID compatible object

# or
pip install uuid6
import uuid6
uuid6.uuid7()

Use v7 for primary keys. It sorts by creation time and keeps PostgreSQL and MySQL indexes tidy. Details on the v7 page.

Other versions

uuid.uuid1()                                   # time based, uses your MAC address by default
uuid.uuid1(node=uuid.getnode() | (1 << 40))   # or pass a random node with the multicast bit
uuid.uuid5(uuid.NAMESPACE_DNS, "example.com")  # name based, deterministic
uuid.uuid3(uuid.NAMESPACE_URL, "https://example.com/a")

Parse and validate

def is_uuid(value: str) -> bool:
    try:
        uuid.UUID(value)
        return True
    except ValueError:
        return False

u = uuid.UUID("{F47AC10B-58CC-4372-A567-0E02B2C3D479}")   # braces and uppercase accepted
u.version      # 4
u.variant      # 'specified in RFC 4122'

The constructor is generous: it accepts braces, the urn:uuid: prefix and 32 hex characters without hyphens. If you need strict 8-4-4-4-12 input, check with a regex first, see our regex guide.

Django and SQLAlchemy

# Django
class Order(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

# SQLAlchemy 2.0
from sqlalchemy import Uuid
id: Mapped[uuid.UUID] = mapped_column(Uuid, primary_key=True, default=uuid.uuid4)

Pass the function, uuid.uuid4, not a call, uuid.uuid4(). The second form generates one value at import time and every row gets the same id.

Mistakes to avoid

• uuid1 leaks your MAC address unless you pass a node. For anything that leaves your machine, use uuid4 or uuid7.
• UUID objects are not strings. Compare with other UUID objects or convert both sides.
• Do not seed random and expect unique ids. uuid4 uses os.urandom, which is correct. Rolling your own from random.getrandbits is not.

Frequently asked questions

How do I get a UUID as a plain string in Python?

Wrap it in str(): str(uuid.uuid4()). For 32 characters without hyphens use .hex.

Is uuid.uuid4() cryptographically secure?

Yes. It reads 16 bytes from os.urandom, the operating system's secure random source, then sets the version and variant bits.

How do I generate a UUID v7 in Python?

On Python 3.14 or newer, uuid.uuid7(). On older versions, pip install uuid-utils or uuid6 and call uuid7() from that package.