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Date Format Converter

Reformat dates between common formats.

beats fecha.dev edge: strftime + relative output
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About Date Format Converter

Parse any common date string — ISO 8601, RFC 2822, locale, custom strftime patterns, Unix epoch — and re-emit as any other format. Get relative output like "3 hours ago", or build a strftime pattern with the live cheatsheet. All parsing runs in your browser.

Why so many date formats?

Each ecosystem standardized on its own. ISO 8601 is unambiguous and machine-friendly. RFC 2822 is what email and HTTP use. Locale formats are what users expect. Unix timestamps are what databases store. strftime patterns are how you build custom output. Round-tripping between them is a daily task in any system that crosses ecosystem boundaries.

The formats that matter

FormatExampleWhen it appears
ISO 86012024-01-15T14:30:00ZAPIs, JSON, logs
RFC 2822Mon, 15 Jan 2024 14:30:00 +0000Email, HTTP headers
Unix seconds1705329000DB timestamps, JWT exp
Unix milliseconds1705329000000JavaScript Date
US locale1/15/2024 2:30 PMUI for US users
EU locale15/01/2024 14:30UI for EU users
Relative3 hours agoUI everywhere
strftime%Y-%m-%d %H:%MLogs, custom formats

Common workflows

Convert from your DB timestamp to a UI string. Paste the ISO value, pick locale + relative mode for the user-facing display.

Build a strftime pattern. Type the desired output, the cheatsheet reveals which tokens you need. Useful when porting code between Python’s datetime.strftime and Postgres to_char.

Verify a parsing error. API returns a date string your code rejects. Paste here. If we parse it cleanly, the bug is in your code; if we also fail, the API is sending garbage.

Translate between locale forms. US sends 1/15/2024, your German user sees 15.1.2024. Confirm the conversion before deploying.

Why a tool

Most languages have a strong date library — Python datetime, JS date-fns or Temporal, Java java.time. They are exhaustive but not always quick to test. A live tester gives you immediate feedback, and the strftime cheatsheet pins itself in muscle memory.

Frequently asked questions

What date formats does it recognize?
ISO 8601 (2024-01-15T14:30:00Z), RFC 2822 (Mon, 15 Jan 2024 14:30:00 +0000), locale forms (1/15/2024, 15.01.2024), Unix timestamps (s, ms, μs, ns), and human strings parsed via the browser's Date.parse.
What is strftime?
A pattern language for formatting dates — %Y-%m-%d for ISO date, %H:%M:%S for time. C-derived, supported by every major language. The cheatsheet on the right lists every token.
Why does my date show as the wrong day?
Almost always timezone. 2024-01-15T00:00:00Z is midnight UTC, which can be Jan 14 evening in your local zone. Toggle UTC mode to see the absolute time.
Can it output relative time?
Yes — Relative mode emits "3 hours ago", "in 2 days", "yesterday at 3:14 PM" using Intl.RelativeTimeFormat.
Does it handle locales?
Yes. Pick a locale — output formats appropriately (en-US uses MM/DD/YYYY, en-GB uses DD/MM/YYYY, de-DE uses DD.MM.YYYY).
Is the date sent anywhere?
No. All parsing and formatting run in the browser via native Intl APIs. Your dates stay local.

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Last updated: 2025-01-15