Referral code, invite code, referral link: are they different?
No. Axiom's sign-up box says invite code, and its documents say referral link. They are the same thing in two forms: the code is join10, and the link https://axiom.trade/@join10 carries that code for you.
When is the code applied?
Once, during sign-up. The box is part of the sign-up form, so the moment to use a code is before you confirm a new account.
What changes after I sign up with a code?
Your trading fees are 10% lower, according to Axiom's referral page. Nothing else about the account changes. The fee line on your first trade shows the rate you really pay.
Why do codes only work on new accounts?
Axiom's terms say current or former users do not count as new users. Section 14 also rules out self-referral and multiple accounts, so a second account is not a way around it.
Which code should I use?
Axiom's documents name one discount for referred users: 10%. On that basis no working code gives you more than another, so what matters is that it reaches the box. Look for a page that shows when it was last tested, and read the fee line on your first trade.
How does 10% off fit with Axiom's ranks?
Axiom has its own volume ranks, from Wood to Champion, with SOL cashback that is separate from any code. Its fee page lists them. Its documents do not say how the discount and the cashback combine, so this guide does not guess.
What are the common mistakes?
Opening the link on a laptop and signing up on a phone. Waiting more than an hour. Pressing Sign Up while the box is empty. Typing the code in the wrong case: use join10, in lowercase. Paying someone for a code, which is never needed.
A worked example
Say you make 20 trades of $500 in a month, so $10,000 in total. Axiom's net fee starts at 1%, which would be $100 in fees. With 10% off, the same trades cost $90, and you keep $10. Your real rate depends on your rank, and the fee line on each trade shows it.
Sources
Axiom's referral page, Axiom's fee page, and this guide's test log. The same facts are in a data table with dates.