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UTC strftime Format Playground
Format an explicit timestamp using a documented portable subset of strftime tokens in UTC.
Zoned timestamp, Format string
strftime-format-playground.json (complete report and generated source where applicable)
Browser only
Runs locally in your browser. Your files, pasted content and generated output are not uploaded. Reset clears this tool’s working data.
This tool needs JavaScript. If it does not load, refresh the page and try again.
How to use this tool
- Enter values using the displayed examples; observe the documented input shape and limits.
- Choose Calculate result. Review the complete JSON report and any generated source text it contains.
- Download result to save the complete report; copy generated source into your project when relevant. Reset restores examples and clears output.
Examples
Zoned timestamp: 2026-10-23T01:02:03Z
Format string: %A %F %T %Z (day %j)
Limitations
- Supports %Y %m %d %H %M %S %j %w %u %a %A %b %B %F %T %z %Z and %%. English names only; unknown directives refused; no locale or local timezone.
- Maximum 100,000 UTF-16 units per field, 400,000 UTF-8 combined input bytes, 4 MiB output and 30 seconds in a local worker. Tool-specific bounds may be tighter.
- Generated source is contained in the JSON download and is never executed. Local inspection does not verify remote systems or establish standards certification.
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