Real-world workflow
Use CaseDecode API created_at Unix Timestamps
Turn opaque Unix created_at / updated_at / expires_at values into readable UTC and local dates while catching seconds vs milliseconds bugs.
The problem
JSON payloads ship created_at: 1735689600 or expiresAt: 1735689600000. Logs paste the same integers. Without converting, you cannot tell whether a token expired yesterday or in 50,000 AD — the classic seconds-vs-milliseconds bug.
Who this is for
Backend and frontend developers, QA, and support engineers reading API responses and server logs.
Steps
- Copy the integer from the payload or log line.
- Count digits: ~10 → seconds; ~13 → milliseconds (for current dates).
- Open Unix Timestamp to Date (already in timestamp → date mode).
- Paste the value and read UTC / local / relative time.
- If you need the reverse for a fixture, use Date to Unix Timestamp.
Example
1735689600 → 2025-01-01T00:00:00Z (seconds)
1735689600000 → same instant as milliseconds
Treating the 13-digit value as seconds produces a nonsensical far-future date.
Related
Frequently Asked Questions
Why do I get a date in 1970?
You likely treated milliseconds as seconds (or divided incorrectly). Check digit length first.
Should APIs return Unix or ISO?
Either works if documented. Prefer ISO for public readability; Unix for compact storage. See the ISO vs Unix guide.
Is data uploaded?
No. Conversion runs in your browser.