If you are looking to help with translation of the Arduino IDE, please use Transifex : https://www.transifex.com/projects/p/arduino-ide-15
From version 1.01 of Arduino's IDE, you can choose your preferred language. We need your help in translating a text file that contains all the different strings in the IDE: from menu names to error messages.
Currently supported languages include:
| How many | Language | as it is | code | status |
| 1 | Arabic | العربية | ar | done by Belal Affouri and Ameen Sarsour |
| 2 | Aragonese | Aragonés | an | done by Juan Pablo Martínez Cortés |
| 3 | Catalan | Català | ca | done by Albert Segura |
| 4 | Chinese | 台灣正體 | zh_tw | done by Yehnan |
| 5 | Chinese Simplified | 大陆简体 | zh_cn | done by Ledong |
| 6 | Danish | Dansk | da | done by Anders Bech Mellson |
| 7 | Dutch | Nederlands | nl | done by jo3ri et al. |
| 8 | Estonian | Eesti | et | done by Cougar |
| 9 | English | English | en | done |
| 10 | French | Français | fr | done by carignanboy1 (Canadian) |
| 11 | Filipino | Pilipino | tl | done by Marc Lester Tan |
| 12 | Galician | Galego | gl | done by Diego Prado |
| 13 | Georgian | ქართული ენა | ka_GE | in progress by Giorgi Maghlakelidze et al |
| 14 | German | Deutsch | de | done by Lukas Bestle and Benjamin Hogl |
| 15 | Greek | ελληνικά | el | done by Vasilis Georgitzikis |
| 16 | Hebrew | עברית | he | in progress |
| 17 | Hindi | हिन्दी | hi | in progress |
| 18 | Hungarian | Magyar | hu | done by Robert Cseh |
| 19 | Indonesian | Bahasa Indonesia | id | done by Rininta Andari |
| 20 | Italian | Italiano | it | done by Sara Gallo and Simone Majocchi |
| 21 | Japanese | 日本語 | ja | done by Shigeru Kanemoto |
| 22 | Korean | 한국어 | ko | done by Jinbuhm Kim |
| 23 | Latvian | Latviešu Valoda | lv | done by Kristofers |
| 24 | Lithuanian | Lietuvių Kalba | lt | done by Laimutis Palivonas |
| 25 | Marathi | मराठी | mr | done by Sarvesh S. Karkhanis |
| 26 | Macedonian | македонски јазик | mk | in progress |
| 27 | Nepali | नेपाली | ne | in progress |
| 28 | Norwegian | Norsk | no | done by Rune Fauske |
| 29 | Persian | فارسی | fa | done by Ebrahim Byagowi |
| 30 | Polish | Język Polski | pl | done by Maciej and Maciej Wójciga |
| 31 | Portuguese (Brazil) | Português | pt_br | done by robmachado et al |
| 32 | Portuguese (Portugal) | Português | pt_pt | done by Nigel Randsley |
| 33 | Romanian | Limba Română | ro | done by Pop Gheorghe |
| 34 | Russian | русский язык | ru | done by Stanislav and Evgeniy |
| 35 | Slovene | Slovenski Jezik | sl | in progress |
| 36 | Spanish | Español | es | done by Juan Gomez et al |
| 37 | Swedish | Svenska | sv | in progress |
| 38 | Tamil | தமிழ் | ta | done by Ram Kumar Y |
| 39 | Turkish | Türkçe | tr | in progress |
If you want to contribute a translation or collaborate on an in process translation, please visit Transifex : https://www.transifex.com/projects/p/arduino-ide-15 where you can see the list of complete and partial translations.