Timestamp → Date
Date → Timestamp
Convert Unix Timestamps & Dates
Paste a Unix timestamp and the tool renders it simultaneously as a UTC string, your local time, an ISO 8601 instant, and a relative expression like "3 hours ago". Paste a date string or pick a date and the conversion runs the other way, producing the epoch value in both seconds and milliseconds. A live clock ticks the current timestamp in both units so you always have a reference value.
This is the tool for decoding the created_at field from an API response, reading a log line where the timestamp is numeric, scheduling something against a fixed epoch value, debugging a timezone mismatch where client and server disagree, or building a test fixture that requires a precise instant in both formats. It also helps explain to a teammate exactly which instant a numeric timestamp refers to.
Both second-precision and millisecond-precision inputs are detected automatically by magnitude — values above roughly 10^12 are treated as milliseconds and anything smaller as seconds. Negative timestamps (before 1970) and future timestamps are accepted. All formats are copyable in one click, and the ISO 8601 output is the safe choice when the destination system might be in a different timezone.
Conversion is pure JavaScript Date math running in your browser — no API call, no network round-trip.
About this tool
Unix timestamps count the seconds since January 1, 1970 (the Unix epoch). They're widely used in APIs, databases, and log files. This tool handles both second and millisecond precision timestamps.
- Two-way conversion (timestamp ↔ date)
- Live current timestamp display
- UTC, local, ISO 8601, relative formats
- Handles seconds and milliseconds
100% client-side. Your inputs never leave your browser. Ads via AdSense (consent required).
Frequently asked questions
How do I convert between Unix epoch and ISO 8601?
Paste a Unix timestamp (seconds or milliseconds) and the tool converts it to ISO 8601 in UTC plus your local timezone. Or paste an ISO 8601 string (2026-04-16T12:00:00Z) and it converts back to epoch. Millisecond precision is preserved both directions. The tool auto-detects whether your input is seconds (10 digits) or milliseconds (13 digits) so you don't have to pick.
Is the timestamp converter free?
Yes, fully free, no signup, no usage cap. Convert as many timestamps as you like — useful for log analysis, database debugging, API payload inspection. JSONCraft has a single open tier across every tool; the timestamp converter is as unrestricted as the rest.
Does the timestamp converter upload my input?
No. Conversions run in your browser using native Date math and Intl.DateTimeFormat. Nothing is transmitted — relevant because log timestamps often come alongside user IDs, trace IDs or request bodies you're debugging. You can paste whole log lines to extract and convert the timestamp without leaking the surrounding context.
How are timezones handled?
Unix epoch is timezone-agnostic (always UTC). ISO 8601 output shows both UTC (with Z suffix) and your browser's local timezone with the offset (-05:00, +01:00). You can also pick a specific timezone from a dropdown to convert into, which is handy when scheduling or debugging across regions. Millisecond values round-trip exactly; sub-millisecond precision is truncated (JavaScript Date's limit).
What's the difference between seconds and milliseconds in epoch time?
Unix tradition (C time_t, most shell tools) uses seconds since 1970-01-01 UTC — 10-digit values in current era. JavaScript, Java and most modern APIs use milliseconds — 13-digit values. Mixing them is a common bug: a seconds timestamp interpreted as milliseconds yields a date in 1970; milliseconds as seconds yields a date in the year 33,658. The tool auto-detects based on magnitude to avoid this.