Cai sits next to 4 phonetic neighbors — Kai, Kay, and Cay are the closest matches by sound. Most share Cai's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"rejoice, delight"
"greatest stream (via Maxwell)"
"victors garland"
"a day's travel, expedition"
"wise protector from the valley"
"little dark one"
"beloved"
"high will, desiring much"
"powerful and brave"
"inspired counsel"
"liberator, deliverer"
"God is just, justice of God"
"rhythm, flow, cadence"
"variant of Caleb, meaning faithful"
"crooked nose, bent river"
"powerful natural force"
"man from the mountain"
"cowherd's descendant"
"invented blend of Jared and Gareth"
"glory-power"
"to tame, subdue"
Similar sound: These names share phonetic patterns with Cai — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin via Welsh origins, giving them the same cultural heritage as Cai.
Rhythm: Cai is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.