Datetime Serialisation
JSON does not natively support datetime. Use ISO 8601 strings for APIs and serialise consistently throughout your stack.
Python
Intermediate
4 min read
Serialising Datetimes
Example
import json
from datetime import datetime, timezone
class DateTimeEncoder(json.JSONEncoder):
def default(self, obj):
if isinstance(obj, datetime):
return obj.astimezone(timezone.utc).isoformat()
return super().default(obj)
data = {"created": datetime.now(tz=timezone.utc), "name": "Alice"}
json_str = json.dumps(data, cls=DateTimeEncoder)
# Deserialise
parsed = datetime.fromisoformat(json.loads(json_str)["created"]) Pro Tip
Always serialise to UTC ISO 8601 — let the frontend convert to the user's local timezone.