How mortgage brokers get paid
On most prime mortgages the lender pays the broker a finder's fee at closing, so the advice costs you nothing directly; on alternative and private deals a broker fee usually applies and must be disclosed to you in writing.
On a prime mortgage with an A-lender (a big bank or a monoline), you generally do not pay the broker directly. The lender pays them a finder's fee, commonly somewhere around 0.5% to 1.1% of the mortgage amount, and it usually rises with the length of the term. Many lenders also run volume programs: a brokerage that sends a lender more business can unlock better payout rates, faster approvals, or sharper pricing for its clients.
Compensation in this industry is regulated and disclosable. It is completely fair to ask any broker how they are paid and how many lenders they considered for your file, and a good broker answers both questions plainly. A tool like this one helps you hold up your end of that conversation: the match list here is ranked purely by fit against the full lender database, so you arrive with an independent shortlist rather than starting from zero.
On B-lenders, alternative lenders, MICs, and private lenders, the money works differently. These deals typically carry a lender fee and often a broker fee too (frequently 1% to 2% or more of the loan), and that cost is usually paid by you, either deducted from the mortgage advance or added to the balance. That is not automatically a bad thing (these lenders take on harder files), but the fee must be disclosed to you in writing before you commit, and you should understand you are paying it.