An NDA on Upwork is a non-disclosure agreement a client asks a freelancer or agency to sign, either before sharing details of a job or as part of the contract, to keep the client's information confidential.
Clients use NDAs at two points. Before a contract, when the job post is vague on purpose and the client wants to describe the real project only to shortlisted candidates, the NDA is attached to the post or sent in Messages and signed before the details follow. During a contract, when the work touches customer data, unreleased products or source code, the NDA sits alongside the contract terms and survives it. Upwork does not supply the document or witness it; the client brings their own, and the freelancer signs it as they would any contract. The Optional Service Contract Terms that apply by default already contain a confidentiality clause, so an NDA adds specificity and duration rather than creating an obligation from nothing.
For the freelancer or agency the practical effect is on the portfolio: work under an NDA cannot be shown or described without permission, which is a real cost for an agency whose next client wants to see examples. Asking for a portfolio carve-out before signing is reasonable, as is declining an NDA that reaches beyond the project. Signing an NDA outside Upwork's tooling is fine; it does not move the relationship off the platform, and payment must still go through Upwork.
An NDA cannot override Upwork's own terms. It cannot require payment outside the platform, forbid honest feedback or stop a freelancer from reporting a breach to Upwork, and Upwork may read the Messages record whatever the NDA says.
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.