This came up in our alerts, so just some comments:

A major reason for any incompleteness is that Xinjiang in general is an information vacuum, which is something that people in over 90% of the world would struggle to get their heads around, never having lived in such a controlled place. You cannot just call local authorities and have them send you relevant information, or consult local government websites/databases, or simply call your friends there and ask, because them telling you could be seen as leaking secrets, collaborating with foreign forces, etc. Of course, that doesn't mean that none of the above ever happen (in rare cases, a local office might actually say something, or an official database might happen to give someone's court verdict, or someone there is brave enough to share something, but this is a tiny fraction of cases). So, we compile all the info there is, crosscheck what is possible when it becomes possible, and let users make their own judgements.

When the project started in 2018, a lot relied on personal testimony from relatives, a lot of it from Kazakhs of Xinjiang origin in Kazakhstan, who put together 1000s of testimony videos and uploaded them on YouTube, with some Uyghurs around the world also following suit, though in smaller numbers. For a while, this was the only real way, even if very imperfect, to get information about what was happening to the concrete individuals there. Starting in early 2020, this started to change as more government and police documents started to leak or get hacked, in some cases containing entire lists of people in villages or towns who were detained, and which could be effectively crosschecked because these documents usually contain their ID numbers. Because many of these were obtained through different and independent channels, they essentially corroborate one another's validity by all the matching details there are, in addition to corroborating many of the personal testimonies, when the people testified for have appeared in these documents. In our experience, there has not been a document leaked/hacked that we've analyzed so far that has looked inauthentic, or the number of inconsistencies would be too great (which is something we are on the lookout for). Today, the database is largely sourced directly from police and government records, and relies significantly less on personal testimony.

We strongly recommend that people read (or skim, if too long) the primary-evidence report that we update in real time: https://shahit.biz/xjvictims_primary.pdf. Everything that's in there (1100+ pages) is raw evidence from the ground, the majority directly from the government/police and translated/curated for those who do not know enough Chinese to look at the originals themselves (which we also make available).

It's hard to ignore people who post lazy conclusions like "there's propaganda on both sides, and each side has their own story, so we don't know the truth". This actually sounds like what someone from the pro-CCP camp would write, actually, since that sort of obfuscation is precisely what the authorities there would desire, muddying the waters and shelving the topic while they continue to get away with the acts they've committed. If you actually try to analyze who the arguing sides are, you'll see that basically any Uyghur abroad is horrified and traumatized by what's happening (just find an Uyghur restaurant or community in your vicinity and ask), as well as every researcher/academic who has lived in Xinjiang and has significant connections there, many of whom have publicly worked to raise this issue. On the other side, you have China-based online influencers, many of whom have no experience in the Xinjiang region but who in late 2019 suddenly started repeating the government propaganda talking points and have been magnified by the state apparatus, or Chinese government officials, or officials from Muslim countries that depend very heavily on China and are not exactly free states themselves (again, with no real authority to speak about Xinjiang). So, it is logically problematic to treat these as equally legitimate and try to make something that's pretty clear cut look gray.

However, it is not really our mission to convince every single online user of the validity of what we do either, since our three main audiences are:

1) The Chinese police and authorities, who seem to visit us daily and whose attention we want the most, so that they may reflect on what they're doing and whom they're doing it to.
2) Professionals, who actually know the region, work/research it seriously, and need our database to have a better picture of what exactly has happened and continues to happen.
3) The general masses who are capable of critical and independent thinking, and who can go through all the evidence and, using their own experience in establishing facts and appraising the value of information sources, make up their own mind regarding the issue and whether or not they want to do something about it. (The general lazy internet user for whom Xinjiang is just another entertaining news headline is not in this group, naturally.)