can i test the welcome message without anybody joining?

yes. ,welcome test posts it where you ran it, so nobody has to join.

can i use a welcome message from another bot?

yes. fray reads the {embed} script most bots use, and both {user.mention} and {user_name} spellings.

yes. ,welcome delete 30s takes it away after thirty seconds.

run ,welcome on its own. it says what's set, and what's stopping it from sending.

test it without anybody joining: test posts the message where you ran it, so you see exactly what a new member will.
scripts from other bots paste in: fray reads the {embed} script most bots use, and both variable spellings, so a message you already have needs no editing.
cards, not flat embeds: titles, galleries of up to ten pictures, fields, buttons and dividers, drawn as discord's newer components.
quiet during a raid: past ten joins in ten seconds greetings stop, so a raid never turns into a wall of welcomes.

,welcome channel #general
,welcome message hello {user.mention}, you're our {server.count.ordinal} member
,welcome test

every option is on the docs page.

can i test the welcome message without anybody joining?: yes. ,welcome test posts it where you ran it, so nobody has to join.
can i use a welcome message from another bot?: yes. fray reads the {embed} script most bots use, and both {user.mention} and {user_name} spellings.
can the welcome delete itself?: yes. ,welcome delete 30s takes it away after thirty seconds.
why isn't my welcome sending?: run ,welcome on its own. it says what's set, and what's stopping it from sending.

fray covers moderation, tickets, giveaways, reposts, roblox and ai, so a server doesn't need a separate bot for each of them.