There are 3 main patterns according to verb endings: -ar, -er and -ir. For -ar verbs in Present tense it is I -o, informal you singular -as, formal you singular -a, he/she/it -a, we -amos, plural you -an, they -an. For -er is -o, -es, -e, -emos, -en, -en. For -ir is -o, -es, -e, -imos, -en, -en. For every tense there different patterns, you should search for a "conjugador"/"conjugator".

These patterns cover regular verbs (don't change the base word) and they are appliable at some point to most irregular verbs.

Www.verbly.io is a fantastic site to learn and practice the conjugation of Spanish verbs - it covers all the tenses, regular, irregular, etc. very easy to use. Verbly is made by Andy Cloke