Unix Timestamp Converter

Time Is a Number — and That Number Is Everywhere

Open any API response, database row, log file, or JWT token and there's a good chance you'll find a timestamp that looks something like 1700000000 or 1700000000000. These aren't errors. They're Unix timestamps — a count of seconds (or milliseconds) elapsed since January 1, 1970, 00:00:00 UTC. The Unix epoch.

Computers love this format because it's a single integer: simple to store, compare, sort, and do arithmetic on. Humans hate it because 1700000000 means nothing without conversion. This tool bridges that gap — paste in a timestamp and instantly see the UTC date, your local date, the ISO 8601 string, and how long ago or from now that moment is.

Seconds vs Milliseconds: The Trap Developers Fall Into

The Unix standard specifies seconds. Most operating system APIs, shell commands, and traditional tools use seconds. But JavaScript's Date.now() returns milliseconds, and so does Java's System.currentTimeMillis(). Many modern web APIs and mobile SDKs follow JavaScript's lead. This creates a classic bug: treating a millisecond timestamp as seconds produces a date in the year 2023... of 556781. This tool auto-detects milliseconds vs seconds by checking magnitude, so you get the right answer without having to figure out which format you're dealing with.

The Four Representations This Tool Shows

Any moment in time can be expressed in multiple ways, and different systems expect different forms. UTC is the timezone-neutral representation — the same number everywhere on Earth. Local time adjusts for your browser's timezone and daylight saving offset. ISO 8601 is the international standard string format (e.g., 2024-11-14T22:13:20Z) that is unambiguous and sortable — required for most modern APIs, logging systems, and configuration files. Relative time tells you how long ago or how far in the future the timestamp is from right now, which is what you actually want when debugging a "why did this happen?" question.

Debugging API Timestamps in Real Work

• JWT expiry verification: JWT tokens contain an exp claim — a Unix timestamp for when the token expires. Decode the JWT with the Base64 Encoder, then paste the exp value here to see whether the token has expired and when it was issued.
• Reading database audit columns: created_at and updated_at columns in PostgreSQL, MySQL, and MongoDB are often returned as timestamps in API responses. Paste the value here to see the human-readable equivalent without writing a query.
• API response debugging: JSON responses from payment APIs, analytics platforms, and cloud services routinely contain timestamps. After using the JSON Formatter to find the timestamp field, convert it here.
• Log file analysis: Structured log lines from Node.js, Python logging, and most cloud services include Unix timestamps. Convert them here to correlate with event timelines without writing a script.
• Date arithmetic: Convert two timestamps to see the difference in seconds, then reason about whether a 3600-second gap means exactly one hour, or whether a daylight saving transition occurred.

The Year 2038 Problem — Still Relevant

Systems that store Unix timestamps as signed 32-bit integers will overflow at 03:14:07 UTC on January 19, 2038 — when the counter exceeds the maximum value of 2,147,483,647. After that second, the integer wraps to a large negative number, interpreting timestamps as dates in 1901. Modern 64-bit systems are unaffected (their timestamps can represent dates up to the year 292 billion), but embedded systems, legacy databases, and old 32-bit systems may still be vulnerable. This tool uses JavaScript's 64-bit floats, which handle dates well beyond any practical concern.

✓Verified by ToollyX Team · Last updated June 2026