Unix timestamps appear everywhere in backend systems—database records, API responses, log files, JWT tokens, authentication cookies. When debugging production issues, I constantly need to translate timestamps like 1735171200 into readable dates like '2024-12-26 00:00:00 UTC' to understand when events occurred. This converter handles both seconds and milliseconds timestamps (JavaScript uses milliseconds, most other systems use seconds), converts to/from multiple timezones, and shows relative time ('5 hours ago'). I added batch conversion because incident investigation often involves comparing dozens of timestamps from logs. The tool also validates expiration times in JWTs—paste an exp claim value and instantly see if the token is expired.
How to Use
Enter a Unix timestamp (seconds since January 1, 1970 UTC) in the input field—the tool auto-detects seconds vs milliseconds format. It displays: UTC date/time, your local timezone conversion, ISO 8601 format (for APIs), relative time ('2 hours ago'), and day of week. To convert date to timestamp: click 'Date to Timestamp', pick a date/time, select timezone, get the Unix timestamp. Batch mode: paste multiple timestamps (one per line) to convert all at once—useful for log analysis. The 'Current timestamp' button shows right now in Unix time, helpful when comparing with database queries or setting future expiration times.
Common Use Cases
JWT Expiration
JWT payload shows `"exp": 1735430400`—paste here to see it expires on 'Dec 28, 2024 16:00 UTC', compare with current time to check if token is valid.
Database Debugging
Query returns created_at as 1704067200—convert to '2024-01-01 00:00:00' to understand record age.
Log Investigation
Application logs show error at timestamp 1735344567—convert to see it happened during deployment window.
API Integration
API documentation says token expires 3600 seconds after issue—calculate future timestamp for testing: current + 3600.
Timezone Coordination
Schedule task at '2024-12-31 23:00 EST'—convert to Unix timestamp to store in UTC-based system.
Rate Limiting
Implement 'next allowed request at' using Unix timestamp—easy to compare and cache.
Limitations & Important Notes
Unix timestamps represent UTC time—displayed 'local' times depend on your browser's timezone setting, which may not match the server timezone you're debugging. The standard Unix timestamp (seconds since epoch) works until year 2038 (2^31 overflow for 32-bit signed integers)—most modern systems use 64-bit timestamps or milliseconds to avoid this. Timestamps before 1970 (negative numbers) are valid but less common and may cause issues in some systems. Leap seconds are not represented in Unix time—timestamps 'skip' leap seconds, which matters for precise scientific timing but not typical web applications. Time range: this tool handles approximately years 1900-2100 reliably; extreme dates may have conversion issues. For financial or legal date-critical applications, use specialized libraries that handle timezone database updates (IANA tzdata) and DST transitions correctly.
timestamp-converter/example.py