Truncate Dates in JSON Files Online
Truncate date and timestamp columns in JSON files to a chosen precision — year, quarter, month, week, day, hour, or minute — directly in your browser. Rounds timestamps down to the start of each period. No upload required.
About this tool
Round every timestamp in a JSON file down to the start of a chosen time period — year, quarter, month, week, day, hour, or minute. This is the standard date_trunc operation used in SQL for time-series bucketing and GROUP BY aggregation. Common uses include grouping events into monthly or weekly buckets, aligning sensor readings to hour boundaries, and stripping time components before joining on date. The tool casts text columns automatically, replaces or appends the result, and runs entirely in your browser.
Frequently Asked Questions
What does truncating a date to month mean in a JSON file?
It sets the timestamp to midnight on the first day of that month. For example, 2024-03-15 09:45:22 becomes 2024-03-01 00:00:00. The date_trunc function rounds down, never up.
Can I truncate a text date column in a JSON file?
Yes. The tool automatically casts text columns to TIMESTAMP before truncating using TRY_CAST. If any values cannot be parsed as dates, those rows will return NULL in the output. Use the Date Parse tool first if you need to standardise the format.
What is the difference between date truncation and date formatting in a JSON file?
Truncation changes the underlying date value — it rounds it down to the nearest period. Formatting only changes how the date is displayed as text without altering the value. Use truncation when you want to group timestamps into buckets for aggregation or filtering.
Is my data private?
Yes — completely. Your file is never uploaded to any server. Everything runs locally in your browser using WebAssembly — processing happens entirely inside your tab. Once you close the tab, nothing is retained.
What is the maximum file size?
The free limit is 50 MB. For larger files, performance depends on your device's available memory — most modern machines handle 500 MB to 1 GB comfortably.
Related Tools
Add Moving Average to JSON Files Online
Add a moving average, rolling sum, rolling min, or rolling max column to JSON files directly in your browser. Choose window size, order-by column, and optional partitioning — no upload required.
Search Text in JSON Files Online
Search for text across all string columns in JSON files directly in your browser. Filter rows to only those containing your search term and download the results — no upload required.
Get Top N Rows from JSON Files Online
Extract the top N rows per group from JSON files directly in your browser. Get the top 5 products per category, highest scores per team, or any ranked subset — no upload required.
Add Percent of Total to JSON Files Online
Add a percentage-of-total column to JSON files directly in your browser. Show each row's share of the grand total, or the share within each group — no upload required.
Parse URL Column in JSON Files Online
Parse URL columns in JSON files and extract host, path, query string, and fragment into separate columns — directly in your browser, no upload required.