Timestamp Converter
Convert Unix timestamps and readable dates to compare seconds, milliseconds, UTC output and local browser display.
Tool Workspace
Processing is intended to run locally in your browser whenever possible. Avoid pasting production secrets, access tokens, private keys or sensitive business data into any online tool unless you fully understand the risk.
Ready. Processing runs in your browser.
Core Features
- Convert Unix seconds and milliseconds.
- Show readable UTC and local dates.
- Help identify off-by-1000 timestamp bugs.
- Prepare examples for API debugging.
How to Use
- Paste a Unix timestamp or readable date string.
- Check whether the value is in seconds or milliseconds.
- Compare UTC and local output before using the value.
- Copy the converted result for debugging notes or tests.
Common Errors
- Treating milliseconds as seconds.
- Treating seconds as milliseconds.
- Ignoring timezone offsets.
- Assuming JavaScript Date displays UTC by default.
Real Developer Use Cases
- Debugging API expiry timestamps.
- Checking log event times across time zones.
- Preparing test data for date parsing code.
Technical Explanation
Unix timestamps usually represent time since 1970-01-01 UTC, but APIs vary between seconds and milliseconds. JavaScript commonly uses milliseconds, while many backend systems expose seconds. A converter helps developers catch scale mistakes, compare UTC and local interpretations and explain time values clearly during debugging.
FAQ
Is my input uploaded to your server?
Tool input is processed in the browser for these utilities unless a page explicitly states otherwise.
Can I use this with production secrets?
Do not paste production passwords, private keys, access tokens or sensitive business data into any online tool unless you fully understand the risk.
Why does this page include explanations below the tool?
Developer Data Tools is designed to help users understand the data problem, not just transform input and output.