The manufacturer always tests its product as part of its quality control, and that testing has value. But whoever makes or sells a product has an interest in a good result. An independent laboratory, with no commercial dependence on either, adds a second opinion.
The value of that testing depends on several details: that the laboratory is identifiable and verifiable, that the certificate states the batch number and the date, that it includes the supporting graphs and not just a percentage, and that the sample tested really comes from the batch being sold.
The most transparent approach is for every batch to be publicly searchable with its certificate, so that any buyer can compare the number on their vial with the matching document.
“Third-party testing” with no laboratory name, no batch or no graphs cannot be verified. Independence only adds value if the document makes it possible to check it.
Related terms
Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).