The Vishnu Sahasranaama (thousand names of Lord Vishnu) is a part of the Anushasana Parva of the Mahabharata. It was composed by Sanaka, one of the Kumaras (eternal living Youths) and was transmitted by Bhishma who recited it in the presence of Sri Krishna to the Pandava brothers when he was questioned thus by Yuddhisthira:
"Who is the Being who is the supreme Lord of all, who is the sole refuge of all and by praising whom man gains what is good and attains to salvation?"
The thousand names of Lord Vishnu is the answer that Bhishma gives to this enquiry.
This app provides a pocket reference to the Vishnu Sahasranaama. The verses are presented both in Devanagari and Roman transliteration.
Also be sure to check out these other top-rated apps provided by Sparsh Apps: Sanskrit Primer, Bhagavad Gita