Supplication upon breaking the fast

ذَهَبَ الظَّمَأُ وَابْتَلَّتِ العُرُوقُ, وَثَبَتَ الْأَجْرُ إِنْ شَاءَ اللَّهُ

(The thirst has gone and the veins are quenched, and reward is confirmed, if Allah wills.)

Source: Abu Dawud 2/306.

اللَّهُمَّ إِنِّي أَسْأَلُكَ بِرَحْمَتِكَ الَّتِي وَسِعَتْ كُلَّ شَيْءٍ أَنْ تَغْفِرَ لِي

(O Allah, I ask You by Your mercy which envelopes all things, that You forgive me.)

Source: Ibn Majah 1/557.