How to convert Unix timestamp to date
Convert Unix seconds or milliseconds into readable dates and understand timezone differences in API logs and JWT claims.
Identify seconds versus milliseconds
Open Timestamp Converter and paste the value from your log, database row, API response, or JWT claim. Ten-digit values are usually Unix seconds; thirteen-digit values are usually Unix milliseconds. The converter helps detect the format and displays readable UTC and local dates.
If the resulting year looks far in the future or far in the past, the value may have been interpreted with the wrong unit. Try converting seconds and milliseconds explicitly before assuming the source system is wrong.
Use UTC for debugging conversations
Local time is useful for your own screen, but UTC is safer when multiple developers, servers, and logs are involved. Include the original timestamp and the UTC conversion in incident notes so teammates can compare events across systems.
For auth issues, decode the JWT first, then convert exp and iat. For parsing issues, test date strings with Regex Tester only after confirming the timestamp itself is correct.
Common mistakes
The most common timestamp mistakes are mixing seconds and milliseconds, treating local display time as UTC, and copying truncated values from logs. Keep the original value next to the converted date until the bug is resolved.
Related tools
Converters
OpenTimestamp Converter
Convert Unix seconds, Unix milliseconds, and ISO date strings with readable UTC and local output.
API & Auth
OpenJWT Decoder
Decode JWT headers and payloads, inspect claims, and check expiry fields at a glance.
API & Auth
OpenJWT Expiry Checker
Show whether a JWT is expired, valid, or missing expiry claims with readable timestamps.
Related workflows
JWT Tools
Inspect JWT header and payload claims, check token times, and debug auth failures faster.
Timestamp and Date Tools
Convert Unix timestamps and inspect time values found in APIs, logs, JWTs, and databases.
API Debugging Tools
Inspect the pieces that usually explain API failures: JSON, JWTs, headers, query params, cURL, and status codes.
Log Tools
Clean noisy logs, extract trace and correlation IDs, and connect log output to payload debugging tools.