re: "Is there a way to validate a client as legitimate?"
There are two answers to this question:
Yes.
No.
Both are correct.
The answer is "no" in the sense that there is no "list" you can check. Nor is there a "button" you can click, labelled "Validate Client."
But the answer is "yes" in the sense that an experienced freelancer knows whether or not a client is legitimate or not.
In fact, an experienced freelancer can typically identify scammers/illegitimate climates within only one or two seconds of looking at an invitation from them.
re: "I checked out the business's website and everything looks really good there."
I recommend never doing this.
I never do this.
I have completed hundreds of jobs on Upwork. I hae never Googled a client's name or business.
Although I don't personally Google any clients, I understand the temptation to do so. Experienced Upwork freelancers may can safely Google client names. But Googling client names is very problematic for newbies/inexperienced Upwork freelancers. This is because Googling the client name is a key part of the scams that are most commonly used. Scammers WANT you to Google the names they feed you, because seeing impressive company websites tricks inexperienced freelancers into believing that the clients are legitimate. But really the scammers just copy those names off of the Internet.
The SAFE way to know if a client is legitimate or not is to see how they behave, and to look at their stats on Upwork itself.
re: "I know they must go through some registration process with Upwork"
It is very easy to register as a client.
Clients are NOT vetted.
Scammers simply create fake client accounts as often as they need to.
A single scammer may have created dozens or hundreds of fake account by the time they send you an invitation. When they are caught scamming, Upwork removes their account, and they just create a new one.
re: "if legitimate, maybe a list could be available for freelancers to check before moving forward?"
There will never be a list.
re: "Although I know Upwork still doesn't recommend talking outside of Upwork, right?"
As of June 26, 2020, Upwork does not allow communicating with clients off-platform until an official contract is in place. This means that until you are hired, you must communicate using Upwork's Messages tool.
re: "Is that my red flag, end of story?"
Well, a traditional money scammer usually wants to communicate off-site, NOT through Upwork's Messages tool. BUT: You must still be cautious. The scammes who want to steal your money will usually want to communicate off-site. But there are also scammers who only communicate with the Messages tool. This is more common among scammers who aren't trying to steal money from your bank account, but who trick freelancers into working for free.
So you can't rely ONLY on the fact that a client doesn't ask you to communicate off-platform.
Also: There are MANY clients who are good, honest clients but who don't know about the "no communications off site" rule.
If a prospective client asks you to communicate, you can tell them that you will be happy to do so after you have been hired with an Upwork contract, and that before there is a contract in place, you can communicate with the Messages tool.
When I have mentioned this to legitimate clients, some of them immediately hire me so that they can communicate using their preferred tools, and some of them decide to communicate with me using the Upwork Messages tool.
