IndicTrans2: Towards High-Quality and Accessible Machine Translation Models for
all 22 Scheduled Indian Languages
AI4Bharat, Jay Gala, Pranjal A. Chitale, Raghavan AK, Sumanth
Doddapaneni, Varun Gumma, Aswanth Kumar, Janki Nawale, Anupama Sujatha, Ratish
Puduppully, Vivek Raghavan, Pratyush Kumar, Mitesh M. Khapra, Raj Dabre, Anoop Kunchukuttan
India has a rich linguistic landscape with languages from 4 major language families spoken by
over a billion people. 22 of these languages are listed in the Constitution of India (referred to
as scheduled languages) are the focus of this work. Given the linguistic diversity, high-quality
and accessible Machine Translation (MT) systems are essential in a country like India. Prior to
this work, there was (i) no parallel training data spanning all the 22 languages, (ii) no robust
benchmarks covering all these languages and containing content relevant to India, and (iii) no
existing translation models which support all the 22 scheduled languages of India. In this work,
we aim to address this gap by focusing on the missing pieces required for enabling wide, easy, and
open access to good machine translation systems for all 22 scheduled Indian languages. We identify
four key areas of improvement: curating and creating larger training datasets, creating diverse
and high-quality benchmarks, training multilingual models, and releasing models with open access.
Our first contribution is the release of the Bharat Parallel Corpus Collection (BPCC), the largest
publicly available parallel corpora for Indic languages. BPCC contains a total of 230M bitext
pairs, of which a total of 126M were newly added, including 644K manually translated sentence
pairs created as part of this work. Our second contribution is the release of the first n-way
parallel benchmark covering all 22 Indian languages, featuring diverse domains, Indian-origin
content, and source-original test sets. Next, we present IndicTrans2, the first model to support
all 22 languages, surpassing existing models on multiple existing and new benchmarks created as a
part of this work. Lastly, to promote accessibility and collaboration, we release our models and
associated data with permissive licenses at https://github.com/ai4bharat/IndicTrans2.