Json Date Formatter
Legacy .NET APIs still emit /Date(1700000000000)/, modern services return quoted ISO strings, and front-end developers inherit both in the same GraphQL response. This JSON date formatter accepts either form in one textarea, detects the pattern, and prints a readable local timestamp with supporting detail so you do not mentally divide milliseconds or guess timezone.
It is the bridge tool between strict ISO parsers and raw unix integer converters-optimized for JSON fragments copied from browser devtools, Postman, or log aggregators. Teachers demonstrating API evolution, integrators migrating SOAP to REST, and on-call engineers decoding escaped strings at 2 AM all benefit from a single paste box. Nothing is posted to a formatting service; parsing happens on your machine. Frontend teams migrating legacy Angular services frequently see both /Date/ wrappers and ISO strings in one payload during a single late-night debugging session with sanitized production data samples attached to urgent customer support tickets.
How to Use
- Paste a JSON date value-/Date(ms)/ or a quoted ISO string.
- Click Format JSON date to parse and display.
- Read local time, UTC, and detected format in details.
- Copy readable output into bug tickets or documentation.
- Try both formats side by side when migrating APIs.
Input Field Guide
- JSON date value
- Microsoft /Date(1700000000000)/ or ISO string like "2026-07-13T10:30:00.000Z" from JSON payloads.
Understanding Your Results
The formatter identifies whether input matches /Date(ms)/ or ISO JSON string patterns, then shows human-readable local date-time plus epoch milliseconds for cross-check. Unknown shapes produce a helpful error instead of silent mis-parsing.
Features
- Microsoft /Date(ms)/ support
- ISO JSON string support
- Automatic format detection
- UTC and local display
- Millisecond echo for verification
- Private local parsing
Formula & Calculation Logic
/Date(ms)/ -> extract integer ms; ISO -> Date.parse; display via local timezone formatting.
Real-World Use Cases
- Legacy ASP.NET Web API debugging
- Silverlight and old SharePoint timestamps
- Mixed-version API migration testing
- DevTools network tab date inspection
- Support ticket payload clarification
Practical Examples
/Date(1700000000000)/ -> readable instant with ms echoed.
"2026-07-13T10:30:00.000Z" -> parsed Zulu JSON string to local.
Benefits
- One box for two common JSON date shapes
- Avoids regex mistakes extracting milliseconds
- Keeps customer payloads private
- Faster than spinning up a REPL
Tips & Best Practices
- Include quotes for JSON string values when copying literally.
- Use iso-converter for bare ISO without JSON quoting.
- Use unix-timestamp-converter for raw numeric epochs.
Common Mistakes to Avoid
- Pasting entire JSON objects instead of the date value field.
- Dropping timezone from ISO strings then blaming the parser.
- Expecting named timezone conversion-use timezone calculator.
What is the Json Date Formatter?
Legacy .NET APIs still emit /Date(1700000000000)/, modern services return quoted ISO strings, and front-end developers inherit both in the same GraphQL response. Run it free in your browser on TimerClock.
When should you use the Json Date Formatter?
Open this page when you need Legacy ASP.NET Web API debugging, Silverlight and old SharePoint timestamps, or Mixed-version API migration testing. If that is not your goal, try a related tool linked below.
Troubleshooting the Json Date Formatter
- No sound: Allow audio for this site, unmute the tab, and raise system volume. Some browsers block sound until you interact with the page.
- Timer seems paused in another tab: Keep the Json Date Formatter tab visible for critical sessions, or install TimerClock as a PWA for better background behavior.
- Wrong time shown: Check the device clock and timezone. World and countdown tools also depend on the target zone you selected.
- Settings disappeared: Preferences are stored locally in this browser. Clearing site data removes saved alarms, themes, and recent durations.
About the Json Date Formatter page
Written and updated by the TimerClock team. The live tool stays at the top; the notes below cover setup limits, sound issues, and related pages. Timing uses your device clock. Preferences stay in this browser. See the privacy policy, terms, and contact page if you need help.
Related reading for the Json Date Formatter
Frequently Asked Questions
What JSON date formats are supported?
Microsoft /Date(milliseconds)/ and standard quoted ISO 8601 strings.
Can I paste the whole JSON object?
Paste the date value itself; whole objects may fail detection.
How is this different from iso-converter?
JSON formatter handles /Date(ms)/ plus JSON-quoted ISO; iso-converter targets bare ISO strings.
Are negative /Date/ values supported?
Yes within JavaScript Date limits for pre-1970 instants.
Does it escape strings for output JSON?
It focuses on human-readable display, not re-serialization.
Will single quotes work?
Prefer double quotes matching JSON; detection expects JSON conventions.
What if both patterns appear?
Detection picks the best match; invalid hybrids show errors.
Is JSON uploaded for formatting?
No. Parsing runs locally.