Format Timestamps in JSON Files Online
Reformat timestamp and date columns in JSON files directly in your browser. Convert between ISO 8601, Unix epoch, US date, and custom strftime patterns — no upload required.
Drop your .json file here
or click to browse — max 50 MB
About this tool
Convert date and timestamp columns in a JSON file from one format to another — ISO 8601, Unix epoch, US date, EU date, or a custom strftime pattern. Useful before loading data into databases or BI tools with strict format requirements.
Frequently Asked Questions
What timestamp formats does the JSON timestamp tool support?
ISO 8601, Unix epoch (seconds and milliseconds), US date (MM/DD/YYYY), European date (DD/MM/YYYY), and any custom format using strftime patterns.
What if the tool does not recognise the date format in my JSON file?
Enter a custom strftime pattern in the format field. For example %d/%m/%Y %H:%M:%S matches 31/12/2024 23:59:59. The strftime reference covers all supported tokens.
Does the JSON timestamp tool convert time zones?
No. The tool reformats how a timestamp is displayed but does not shift values between time zones. For timezone conversion use the SQL Query tool with AT TIME ZONE.
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.
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