Background: INPLASY® is an international platform for registering systematic reviews and meta-analysis protocols that was launched in March 2020. INPLASY® provides an online database in which the protocols are maintained as permanent public records and can be accessed on its website (www.inplasy.com).

Methods: We described the database features and registered information of all records published since the launch of the registry on March 31, 2023. Additionally, we analyzed the website statistics dataset to explore user experience and promote data transparency.

Results: Four thousand six hundred fifty-eight records were registered in INPLASY®, and more than 94% of the protocols were published within 24 h. Most of the submissions were from China, followed by Portugal, Taiwan, Malaysia, and Brazil. The INPLASY® website received 386,395 page views from 64,568 visitors during the first three years. The accesses were obtained from 170 countries. Most of the accesses were from China, followed by the US, the UK, and Portugal. The review status “completed and published” was observed in 898 protocols, and these studies were published in 372 different scientific peer-reviewed journals. The features of INPLASY® include the following: (i) INPLASY® identifier, a unique protocol number; (ii) the digital object identifier (DOI) number, the URL of the protocol linked to a specific DOI; (iii) ORCID update, INPLASY® automatically updates authors' ORCID page, including their protocol; and (iv) search tools, the protocols are freely accessible on www.inplasy.com.

Conclusions: INPLASY® has several practical and useful features that should be considered when planning the registration of a systematic review protocol. Furthermore, the sharp increase in the number of protocols registered in INPLASY® in the first three years and the database statistics demonstrate that INPLASY® has become an important source of systematic review protocols. Therefore, authors should access INPLASY® before planning a future review study to avoid unintended duplication of efforts and to obtain timely registration.