OpenTZ: free time zone database and API

Local time, UTC offset and daylight saving rules for 419 time zones in 240+ countries, derived from the IANA tz database. Look a zone up by name, by latitude and longitude, by city or by IP address, convert times between zones, and list every zone, through a simple XML/JSON API.

Register for a free API key — every feature is included, there is no paid tier.

Try it

curl "https://opentz.noomad.org/v2.1/get-time-zone?key=YOUR_API_KEY&format=json&by=zone&zone=Europe/Paris"

{"status":"OK","message":"","countryCode":"FR","countryName":"France","regionName":"","cityName":"","zoneName":"Europe\/Paris","abbreviation":"CEST","gmtOffset":7200,"dst":"1","zoneStart":1774753200,"zoneEnd":1793502000,"nextAbbreviation":"CET","timestamp":1791548015,"formatted":"2026-10-09 12:40:15"}

What you get

• get-time-zone: by zone name or abbreviation, by position, by city (with region and pagination) or by IP address.
• list-time-zone: all zones, filtered by country or name pattern.
• convert-time-zone: convert a timestamp between two zones.
• Download the time zone database as CSV, free under the Creative Commons Attribution licence.

The API reproduces the TimeZoneDB v2.1 request and response format, checked against 160 reference responses of the original service: existing clients only need a new base URL and key.