EDIT: A few specifics I forgot to include. I'm in my late 40's and in the north east US.
Here's what it looks like from where I sit: Older people want to get paid more. If you want to get paid more, you have to be worth more. You don't become worth more by working longer hours - you can't compete with the young on that front. Instead, be worth more by creating fewer bugs, by not creating flawed designs, by knowing that something is a bad idea before it's implemented, and so on. Your experience has to show up in value for your employer, or it isn't worth more money.
So if your experience isn't worth more money, and you still want more money, you have trouble getting a job. It's not ageism, exactly (though ageism could result as hiring people internalize the situation).
I said "you have to be worth more money", but that isn't exactly right. You have to be worth more money, and be able to convince the hiring people that you are worth more money. If their default assumption is "older people aren't worth it", you've got an uphill struggle.
Web dev itself may be a problem. Is experience worth more than knowing the latest framework? Can you learn that framework faster than the younger people?
> Should I make efforts to make myself appear younger when interviewing?
No.
[1] Attorney but also happened to wear Chief Info Security Officer/Chief Privacy Officer hats