Despite having three species of non-human primates in Singapore, most people are only familiar with the long-tailed macaque (Macaca fascicularis). The small and nocturnal Sunda slow loris (Nycticebus coucang) and the elusive Raffles’ banded langur (Presbytis femoralis femoralis) are not known to many. Raising public awareness of the langur in Singapore is one of the objectives of our citizen science project, a partnership with Raffles’ Banded Langur Working Group, NParks, WRS, NSS and NUS. Since August 2016, our citizen scientists have completed three 6-month field surveys, generating information on langur home range and behaviour! On 10 December 2017, together with DataKind and Google Inc., we presented survey results and recruited new volunteers for the 4th round. We also launched a new web application developed for langur facial recognition. A total of 90 people attended and 56 people signed up to carry out the 4th round of citizen science surveys, which happen twice on Saturdays and twice on Sundays for 24 weeks.