Vedic Astrology has an excellent and proven method of horoscope matching based on nakshatras (Lunar Constellations), which is called Ashtakoot milan or simply guna milap.
This Online Kundali Milan method assigns points for factors that influence marriage. More the points, more chances of success of the marriage.
Though this method is not restricted to marriage only and can be used for compatibility analysis between boy and girl with slight modification.
In Ashta-Kuta system of Kundali making, the maximum number of Gunas are 36. If total Gunas between the couple are between 31 and 36 (both inclusive) then the union is excellent, Gunas between 21 and 30 (both inclusive) are very good, Gunas between 17 and 20 (both inclusive) are middling and Gunas between 0 and 16 (both inclusive) are inauspicious.