How they can do it

Doing what? 0o
Are you sure about that?
Of course there is some hacker's over there, but don't jump to quickly on some affirmations that may not be truth...
Maybe they got connected for a few minutes also....

How do you know they're offline when they enter?

Hmm - I'd rather say that maybe there's a bug with site itself showing online users as offline for some reason. Because ofc there's the case that someone made his own script that would enter GAs without physically entering SG itself - but if you see it from multiple people, the auto scripts that werte posted publicly on SG (both ones that stayed and ones that got topics closed) all required having a physical site on for script to analyze it's data. Also not sure how one would enter GA in online - wpuldn't a script have to log into his account and if it did, shouldn't SG mark him as Online?

The site updates "Last online" time every XX (20-25?) minutes.
On your profile, now, I see Last Online: 26 minutes ago, but you posted this thread 12 minutes ago.

Tough its a public secret that there are people using Scripts to enter giveaways ,cause its to hard to press 2 buttons ...
Like even i know a couple of guys who use those ...

When i asked them .. Why ?
Answer : to lazy to enter myself ...

So yeah ... that kinda thing do exist , alltho as some people mentioned the whole last online thing is not really working all that great ;P

A script exist to enter all giveaway on frontpage automatically, but you need to have SteamGift open to use it.

Legal ? Yes it's legal.
It's not against the ToS neither I think.
It's just stupid, and not playing along. And disrespectful for the creator of the giveaway IMO

Becouse i have many of them on skype and steam xD

I don't need a script for it to look like that.
In Steam, under 'Friends' I have marked 'offline', I olny change that if I want to play with friends... and later change it back to offline.
When I come here I sign in to Steam, and when I enter a GA or post here, it says I'm offline (last online cccc).

i close it i receive my answer ty to all