When should I use 639-1 versus 639-2?

Use the two-letter 639-1 code (such as en) for HTML lang attributes, hreflang tags and most web APIs. Use the three-letter 639-2 code (eng) for libraries, bibliographic data and languages that have no two-letter code.

Which 639-2 variant is shown?

These are the 639-2/T (terminology) codes, which match the 639-3 codes most closely. A few languages also have a 639-2/B (bibliographic) variant, but 639-2/T is the form used in modern software.

What is the ISO 639-1 code for English, Spanish and Chinese?

English is en, Spanish is es and Chinese is zh. Their 639-2/T three-letter codes are eng, spa and zho respectively.

Do all languages have a two-letter 639-1 code?

No. ISO 639-1 covers only the most widely used languages — roughly 180. Many languages have only a three-letter 639-2 or 639-3 code, which is why a fallback to the longer code is sometimes needed.

What does the native name column show?

It shows the language endonym — the name speakers use for the language themselves, written in its own script. For example German shows as Deutsch and Russian as Русский.

Can I use these codes in an HTML lang attribute?

Yes. The 639-1 two-letter code goes directly in lang and hreflang attributes, for example lang="fr" for French. Add a region subtag (lang="fr-CA") only when you need to distinguish dialects.

Is anything sent to a server?

No. The language list ships with the page, so every search runs entirely in your browser.

What is the ISO Language Codes Reference?

Free ISO 639 language code reference — search two-letter (639-1) and three-letter (639-2) codes plus native names for every major language. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

ISO Language Codes Reference

Name: ISO Language Codes Reference
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

Get one useful tool a week

Like this tool? Enter your email and we'll send you one genuinely useful Gera tool a week — plus a link to come back to this one. No spam, one-click unsubscribe any time.

ISO 639 is the international standard that assigns short codes to human languages so software, web pages and library systems can label content unambiguously. This reference lets developers, translators and content editors search every major language by English name, native name, two-letter ISO 639-1 code or three-letter ISO 639-2 code, and copy the right one.

How it works

The full language list ships with the page. As you type, every row is matched against four fields at once — English name, native name (endonym), the 639-1 code and the 639-2/T code — and the table filters to the rows that contain your text. There is no lookup request and no API call; filtering is a plain client-side string match.

Each row gives you both code forms so you can pick the one your platform expects:

Field	Example (German)	Where it is used
English name	German	Human-readable UI labels
Native name	Deutsch	Language pickers shown to native speakers
ISO 639-1 (2-letter)	de	HTML lang, hreflang, most web APIs
ISO 639-2/T (3-letter)	deu	Libraries, MARC records, terminology systems

Common use cases and which code to pick

HTML and web development

<!-- 639-1 for the lang attribute -->
<html lang="fr">
<p lang="de">Auf Wiedersehen</p>

<!-- hreflang in SEO for alternate pages -->
<link rel="alternate" hreflang="es" href="https://example.com/es/" />

Use the two-letter 639-1 code for virtually all web contexts. Append a region subtag (hyphen + ISO 3166-1 alpha-2) only when the dialect distinction genuinely matters: pt-BR for Brazilian Portuguese versus pt-PT for European Portuguese, or zh-Hans (simplified) versus zh-Hant (traditional Chinese).

Library and cataloguing systems

MARC 21 bibliographic records use 639-2/B (bibliographic) codes. Most software uses 639-2/T (terminology) codes, which align with 639-3. When in doubt, the 639-2/T form shown in this reference is the safer choice for modern systems.

Quick reference — frequently looked-up codes

Language	639-1	639-2/T	Notes
English	en	eng	Universal default fallback
Spanish	es	spa	20 regional variants; es alone is fine for most
Mandarin Chinese	zh	zho	Use zh-Hans / zh-Hant for script distinction
French	fr	fra
Arabic	ar	ara	RTL; include `dir="rtl"` on the element
Hindi	hi	hin
Portuguese	pt	por	Distinguish pt-BR and pt-PT in hreflang
Russian	ru	rus	Cyrillic script
Japanese	ja	jpn
German	de	deu
Korean	ko	kor
Turkish	tr	tur

Languages with no 639-1 code

ISO 639-1 covers roughly 180 of the most-used languages. Many widely spoken languages — including Hausa, Yoruba, Zulu, and Tibetan — have a 639-2 or 639-3 code but no two-letter code. For HTML, use the shortest available code: if 639-1 exists, use it; otherwise fall back to the 639-2 or 639-3 three-letter code.

All searches run entirely in your browser — nothing you type is uploaded or stored.