Handling Dates and Timestamps in JSON: ISO 8601 vs Epoch
Because JSON has no native Date data type, discover the best practices for representing dates using ISO 8601 strings and Unix timestamps.
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Standard JSON defines numbers, strings, booleans, arrays, objects, and null, but intentionally omits a Date type. Developers must choose between ISO 8601 strings and Unix timestamps.
The Best Practice: ISO 8601 Strings in UTC
Example: `"createdAt": "2026-10-02T18:00:00.000Z"`
Advantages: - Human readable when inspecting API network traffic. - Parses reliably in JavaScript (`new Date("...")`), Python (`datetime.fromisoformat`), and Java. - Explicitly specifies the timezone (always use `Z` for UTC).
Unix Epoch Timestamps (Milliseconds)
Example: `"timestamp": 1790964000000`
Advantages: Extremely compact, easily sortable numerically, no string parsing overhead. However, always document whether your API uses seconds or milliseconds to prevent 1970 date bugs!
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