SmartQueryTools

Parse Dates in JSON Files Online

Parse and convert date columns in JSON files between formats and timezones directly in your browser. Supports ISO 8601, US/EU dates, Unix timestamps, and custom patterns — no upload required.

How to parse Dates in JSON files

  1. Drop your file. The first column is preselected, and the output name defaults to that column name plus _parsed.
  2. Pick the column to parse. The list shows each column's detected type, so you can see whether it is already a DATE or TIMESTAMP or still text.
  3. Choose the input format: Auto-detect, ISO 8601, US date (MM/DD/YYYY), EU date (DD/MM/YYYY), Unix epoch in seconds or milliseconds, or a custom strptime pattern.
  4. Leave both timezones on UTC unless you need a conversion, then pick an output format: ISO 8601, date only, US date, EU date, Unix epoch seconds, or a custom strftime pattern.
  5. Click Parse Dates, check the preview, and download. The parsed column replaces the original column in the same position. A message tells you how many values could not be parsed.

Your file is processed locally in your browser and is never uploaded. The free limit is 50 MB per file; larger files work if your device has the memory for them.

Worked example

A hotel booking system exports check-in times as ISO-style timestamps. The UK finance team wants plain DD/MM/YYYY dates, and one booking still has "TBC" instead of a date.

Input (JSON)

[
  {
    "booking_ref": "HB-5520",
    "guest_country": "IE",
    "check_in": "2026-09-14 15:00:00",
    "nights": 3
  },
  {
    "booking_ref": "HB-5521",
    "guest_country": "DE",
    "check_in": "2026-09-15 11:30:00",
    "nights": 1
  },
  {
    "booking_ref": "HB-5522",
    "guest_country": "FR",
    "check_in": "TBC",
    "nights": 2
  },
  {
    "booking_ref": "HB-5523",
    "guest_country": "GB",
    "check_in": "2026-10-02 18:45:00",
    "nights": 5
  }
]

Settings

  • Column to parse: check_in
  • Output column name: check_in_parsed (the default)
  • Input format: Auto-detect
  • Source and target timezone: UTC (no conversion)
  • Output format: EU date (15/01/2024 style)

Result

booking_refguest_countrycheck_in_parsednights
HB-5520IE14/09/20263
HB-5521DE15/09/20261
HB-5522FRNULL2
HB-5523GB02/10/20265

check_in is replaced by check_in_parsed in the same position, and the other columns are untouched. Auto-detect reads the timestamps and the EU output keeps only the date. "TBC" is not a date, so it becomes NULL instead of stopping the run, and the tool reports 1 value that could not be parsed. The new column is text, because DD/MM/YYYY is a display format rather than a date type.

Working with JSON files

JSON has no date type, so dates arrive as strings. The reader turns a key into a DATE only when every value uses one clear form such as 2026-09-14. Keys in regional forms like 14/09/2026 stay as text, which suits the US, EU and custom modes. Epoch values stored as JSON numbers work with the two Unix epoch modes directly. ISO timestamps ending in Z or an offset such as +02:00 need Auto-detect, which reads the offset. 2026-09-14T15:00:00+02:00 becomes 13:00 UTC.

If a key is missing from some objects, those records get null and stay null after parsing. In the output array the parsed key keeps its place in each object under its new name, and its value is a JSON string. Epoch seconds output is the exception and is written as a JSON number. Dates inside nested objects, such as order.created_at, cannot be selected. Flatten the file first so they become top-level keys.

Frequently Asked Questions

Can I parse ISO timestamps such as 2026-09-14T15:00:00Z?

Use Auto-detect. It accepts a trailing Z, a UTC offset and fractional seconds, and converts offsets to the source time zone. The ISO 8601 mode reads 2026-09-14T15:00:00, the same with a space instead of T, fractional seconds, or a date alone. Values with an offset become empty in ISO 8601 mode.

What happens to JSON objects that do not have the date key?

They get null in the parsed key. Every object in the output array has the same keys, so the key is still present with a null value.

What happens to values that cannot be parsed?

They become empty (NULL) in every mode, and the rest of the column is parsed. After the run the tool tells you how many values failed, so you can check them. Empty cells are not counted as failures.

How does the time zone conversion work?

The source zone is where the times were recorded, and the target zone is the one you want. 14:00 US/Eastern in July becomes 18:00 UTC, and 14:00 in January becomes 19:00 UTC, because daylight saving time is applied. Unix epoch values are always read as UTC, whatever the source zone says.

Does the tool keep the original column?

No. The parsed values replace the source column in the same position, under the output column name. Keep a copy of the original file if you need both.

What type is the parsed column?

Text for every output format except Unix epoch seconds, which is a whole number. ISO 8601 output looks like 2026-09-14T15:00:00 and date-only output like 2026-09-14. Cast the column to DATE or TIMESTAMP afterwards if you need a typed column.

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