Batch converter

No. Every line is converted by page JavaScript on your device — verify in DevTools Network, zero requests are made. Production logs often contain API keys, tokens and user data, which is exactly why this page exists: the old server-side converters see everything you paste.

Up to 10,000 lines. Past that the page refuses with an explicit message instead of freezing your tab — split the file or use the upcoming API. Empty lines are skipped, invalid lines are kept and flagged so line numbers still match your log.

Each line is detected independently by numeric range: seconds, milliseconds, microseconds, nanoseconds. Mixed columns (for example ms from JS logs next to s from backend logs) convert correctly without a mode switch.

The three usual causes: 11–12 digit truncated values, surrounding quotes from CSV exports, and Windows FileTime pasted by mistake. Strip quotes and complete truncated values first.

Yes — Download CSV exports input, detected unit and ISO 8601 columns in the original line order, so you can join it back against your log in a spreadsheet or script. The file is generated in memory from the same local conversion; nothing round-trips through a server.