Client reviews are the star rating and written comment a client leaves on a freelancer or agency when a contract ends, published in the work history on the profile and feeding, together with private feedback, the Job Success Score.
When an Upwork contract closes, both sides are asked for feedback. The client rates the freelancer or agency on several criteria, which Upwork combines into a star rating out of five, and writes a comment; the freelancer rates the client in turn. Upwork's Help Center describes the exchange as double-blind: neither side sees the other's review until both have posted or a period Upwork sets has passed, so a client cannot write their review in reply to the freelancer's. The result appears as public feedback in the profile's work history, next to the contract title, its value and the client's own spend band. A client is also asked a private question about whether they would recommend the freelancer, which is never shown on the profile.
The public review is what prospective clients read; the private answer is a large part of what the Job Success Score computes. The two can diverge. A five-star public review with a lukewarm private answer counts against the score, which is why a freelancer with glowing comments and a score in the eighties is not a contradiction. Reviews are weighted in the score by the size and length of the contract, and a contract that ends with no feedback at all can count against it too.
The freelancer cannot delete a review. A Top Rated freelancer may have one removed from the score periodically, under the feedback removal perk, and a client can revise a review within a window Upwork sets; otherwise the record stands.
How Upwork Insights uses it
This term describes Upwork's own rules or product rather than a figure the index measures; the pages that do carry live figures are the stats and rate pages.