ISO 8601 RFC 3339 (yyyy-mm-dd) for storing dates in software. Any format that that goes in the order of day, month, and year for conversational/presentational purposes, preferable the format is dynamic depending on the user’s locale (even for those that want the month first). There now everyone is happy.
Edit: switched to RFC 3339 since it is a subset of ISO 8601 that is more strict, and I love semantics.
RFC3339 is better than ISO8601 since it doesn’t allow some of the esoteric formats, and allows some useful formats that ISO8601 doesn’t (like separating date and time by a space instead of by T)
For example, 2026-W32-1 is also a valid ISO8601 date: Monday on the 32nd week of 2026. That format isn’t allowed with RFC3339.
Damn it I forgot about the duration part of ISO 8601 (which is also super useful and I love it). I’ll amend it to RFC 3339 to be more exact in what I mean (even though the specified format should prevent the more esoteric formats).
ISO 8601RFC 3339 (yyyy-mm-dd) for storing dates in software. Any format that that goes in the order of day, month, and year for conversational/presentational purposes, preferable the format is dynamic depending on the user’s locale (even for those that want the month first). There now everyone is happy.Edit: switched to RFC 3339 since it is a subset of ISO 8601 that is more strict, and I love semantics.
RFC3339 is better than ISO8601 since it doesn’t allow some of the esoteric formats, and allows some useful formats that ISO8601 doesn’t (like separating date and time by a space instead of by
T)For example,
2026-W32-1is also a valid ISO8601 date: Monday on the 32nd week of 2026. That format isn’t allowed with RFC3339.https://ijmacd.github.io/rfc3339-iso8601/
Damn it I forgot about the duration part of ISO 8601 (which is also super useful and I love it). I’ll amend it to RFC 3339 to be more exact in what I mean (even though the specified format should prevent the more esoteric formats).
Don’t forget about RFC 9557 though, which is an update to 3339 to bring it into closer alignment with ISO 8601 (regarding UTC).