Timestamp Converter
Unix ⇄ Date · Seconds/Milliseconds
Timestamp
Ready
ABOUT
About Timestamp Converter
Quickly convert between Unix timestamps and ISO date strings—troubleshoot logs and API time fields.
Log troubleshooting, JWT exp interpretation, database created_at fields—timestamp conversion is one of the most frequently used "small tools" daily. Mixing seconds and milliseconds causing 1970 or 2286 dates—instant local conversion avoids that.
DEEP DIVE
Learn More About Timestamp Converter
Unix timestamp is seconds (or milliseconds) since 1970-01-01 00:00:00 UTC. Log systems, databases, JWT iat/exp, JavaScript Date.now() all use this format. JSONSort Timestamp tool converts bidirectionally between Unix time and ISO 8601 readable dates, auto-detecting seconds/milliseconds by digit count.
Common daily needs: "what date is this timestamp?", construct specific times for test data, verify JWT expiry time.
Unix timestamps use seconds (10 digits) or milliseconds (13 digits): MySQL UNIX_TIMESTAMP and JWT exp use seconds; JavaScript Date.now() and Java System.currentTimeMillis() use milliseconds. Tool auto-detects by digit count—still confirm against source system docs.
FEATURES
Core capabilities
Unix → Date
Enter timestamp; output ISO 8601 and local timezone readable format.
Date → Unix
Enter date string; output seconds/milliseconds timestamp.
Seconds/milliseconds detection
Auto-detect 10-digit (seconds) vs 13-digit (milliseconds) timestamps.
Multi-timezone display
Show UTC and local timezone simultaneously to avoid confusion.
Instant calculation
All format outputs update immediately on input change.
Local processing
No network requests—works offline.
Current time
One-click fill with current timestamp and ISO string.
Multiple format output
Display ISO 8601, local locale, and Unix seconds/milliseconds simultaneously.
HOW TO USE
How to use
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1
Enter timestamp or date string
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2
View bidirectional conversion results
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3
Copy desired format
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4
Use the sample data button to quickly understand input/output formats
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Copy results to clipboard, or chain with other JSONSort tools
WORKFLOW
Typical workflow
End-to-end workflow from import to export, helping teams standardize Timestamp Converter usage.
Identify source format
Count digits: 10=seconds, 13=milliseconds; or paste ISO date string.
Enter & convert
Paste into input area; view all format outputs.
Cross-verify
Compare with original log text and JWT exp to confirm consistency.
Copy & Use
Copy desired format into test data or documentation.
USE CASES
Use cases
Backend developers
Interpret Unix timestamps in logs to confirm actual event time.
Frontend developers
Construct Date.now() equivalent timestamp for debugging countdown components.
QA engineers
Generate JWT or session test data with specific expiry times.
Data analysis
Convert timestamp fields in CSV/JSON to readable dates for reports.
Log analysis
Cross-reference @timestamp and Unix fields in Splunk/ELK.
Blockchain / Web3
Convert on-chain block timestamp to readable time to verify transaction order.
TIPS
Tips
- 10 digits = seconds, 13 digits = milliseconds—a 1000× difference is the most common error source.
- JWT exp is seconds-level Unix timestamp; JavaScript Date.now() is milliseconds.
- Enter ISO string like 2024-01-15T08:00:00Z to reverse-lookup Unix timestamp.
- When troubleshooting logs, confirm server timezone: UTC vs CST differs by 8 hours.
- Use with JWT tool: after decoding token, paste exp here to see expiry time.
- Database-exported second-level timestamps—multiply by 1000 for JS if needed.
- Seeing 1970-01-01 usually means milliseconds used as seconds—try ×1000.
- Locale display may jump an hour on DST transition days—use UTC as reference.
- After converting JWT exp to date, subtract 5-minute buffer to set token refresh reminder.
- Store in UTC in database; convert to local timezone in presentation layer.
LOCAL VS ONLINE
Local vs online tools
JSONSort stays purely frontend—this comparison shows why local tools fit dev data better.
TROUBLESHOOTING
Common pitfalls & fixes
Issues you may hit in practice and how to handle them—save time on trial and error.
Date off by 8 hours
Tip:UTC vs CST confusion; check Z or +08:00 in ISO string.
13 digits still wrong
Tip:May be microseconds; divide by 1000. Or check for custom epoch.
ISO parse failed
Tip:Confirm format has T separator and timezone; complete partial dates.
Differs from server
Tip:Server clock skew; use NTP-synced authoritative source.
FAQ
FAQ
How to distinguish seconds and milliseconds?
10 digits usually seconds (e.g. 1700000000), 13 digits milliseconds (e.g. 1700000000000). Tool auto-detects.
Does it support timezones?
Output includes both UTC and browser local timezone formats.
Is Y2038 affected?
JavaScript uses 64-bit float for time—no concern before 2038.
Does it support negative timestamps?
Yes. Dates before 1970 correspond to negative Unix timestamps.
What about microsecond timestamps?
16-digit microseconds: divide by 1000 to convert to milliseconds first.
Is data uploaded to a server?
No. All JSONSort tools run locally in your browser—your input is never sent to any backend.
Do I need to sign up or install anything?
No. Open the page and go—no account, no client download, PWA offline cache supported.
How large can files be?
Depends on browser memory; multi-MB data usually runs smoothly. Split very large files or use merge & clean first.