It's all right to spell it 'alright'
Already does not mean all ready. Always does not mean all ways. Also does not mean all so. Although does not mean all though. Almost certainly does not mean all most. And alright? Well, it doesn't always mean all right.
Some people think it's bad to use alright. They demean it as an "illiteratism," a sign of poor education, "not a word," and so on. Why, when we can make a nice and tidy distinction between "Your responses were alright" and "Your responses were all right," do nearly all the people who dispense grammar advice wave you away from this one lest mobs bearing torches and pitchforks appear at your door?
I'll tell you why. And after that, I'll tell you why I want you to ignore them.
It's an impostor.
The other al- words — already, always, also, almost, although — have pedigrees all the way back to Old English, darlings. They're nobility (or, in U.S. terms, members of the Mayflower Society). Yes, there was a word alright a thousand years ago in Old English (they spelled it ealriht then). That word meant "exactly," "entirely," or "straight all the way." It was out of use by a century before Shakespeare was born. This new alright showed up not much more than a century ago and means something quite other than the old alright. It's a parvenu, an arriviste! It's laying claim to a title it did not inherit! Who does it think it is, coming along and trying to join the al- club like some lottery winner?
It's spelled the way a person who didn't know better would spell it.
Why did all right come to be spelled as alright? By analogy with the others, of course. There's also a family name Alright that has been around for centuries (a modified version of Ailright). The spelling seems sensible enough: alright doesn't mean "entirely correct," so why write it as all right? It just seems… alright. Which means, in our sadistically capricious spelling system, that it bears the marks of an inadequate education.
Words are known by the company they keep. And alright came to be associated in literature with various yokels and semi-literate types. It was used as a bit of what's called "eye dialect": you spell a word more as it's pronounced (for example, nollij for knowledge, sed for said, lissen for listen) to give the idea that the speaker wouldn't know how to spell it properly.
You can find stories from the early 1900s with people saying things such as "Ah, that's alright, Father, it's alright, an' I niver'll say wan wurd" — and writing notes such as "She will return soon alright, if you keep quiet. But if you folloe her or take any steps the consequinses will be very serious." So from the very beginning of its appearance alright gained an air of not only an upstart but an ill-bred, poorly educated one.
And to add one more damning detail, an alrightnik, for those who use the term (and it's been in use for 90 years), is a vulgar, self-satisfied arriviste. Just as alright is in the eyes of many.
They're used in the same places.
Already, always, also, and almost are used in many places where you can't use all ready, all ways, all so, and all most. Although is used in many of the same places as though but not all though. But you can use all right and alright in pretty much all the same places. There is a real risk of confusion, although you could make a distinction in the intonation. This also reinforces the idea that alright is a modified version of all right.
So why do I say you should ignore people who tell you not to use alright?
Other similarly formed words are accepted.
If language peevers object to having two slightly different words that were originally the same thing, they will have to do away with the pairs thresh/thrash, raring/rearing, urban/urbane, human/humane, grits/groats, frenetic/frantic, mantle/mantel, and many more. Anyone who would like to electrocute those who use alright should know that a century ago electrocute was mightily inveighed against as a disgusting illiterate neologism. Anyone who would militate against alright should know that less than a hundred years ago there were writers saying there was no such word as militate. And so on.
It increases the expressive potential of the language.
The rules of language exist to serve communication, not vice-versa. Anything that allows the language to express more things with more shades of meaning is good. "The kids are all right" is not "The kids are alright." I have yet to meet a photographer who would say no to a free nice new lens; why on earth would we say no to a word that allows a useful distinction? Especially if it's already been in use for a hundred years?
It's not going away.
Yes, we've had alright for over a century now. Its use has increased fairly steadily over that time. It's used almost five times as much now as it was in 1960. It's not going away. Accept it or consign a useful tool to a dusty corner of the basement.