Foxit PDF Reader (mobile version).

If you only view PDF documents, you can choose Google PDF Viewer, which is an official PDF reader produced by Google. You can view, print, search and copy text in PDF documents anytime and anywhere.

However, due to its very small size, its functions stop here. If you need to take notes on PDF, you need a PDF reader with more comprehensive functions.

Foxit PDF Reader (mobile version) is a feature-rich PDF reading tool. In addition to free PDF reading annotations, it also has many common functions such as PDF editing and PDF conversion. It is still very worthwhile. Just give it a try.

This software is not purely free, but the PDF reading and PDF annotation functions are indeed free.

If the functions are divided into PDF reading and PDF editing, then reading, searching, annotation and other functions related to PDF reading in the software will not cost money.

Document comments also include highlighting, underlining, strikethrough, text box, signature and other functions, which can fully meet everyone's daily PDF reading needs.

As a heavy user of Android tablet reading, I have used Jingdu Tianxia Professional Edition, ezpdf reader, mantano reader, smart device reading, repligo reader, adobe reader, Beam Reader, document to go.

The ones that have been uninstalled include: Adobe, Intelligent Device, and Beam Reader (adobe, document to go, and beam are not necessary in my opinion, so I will not comment on them).

I usually read non-scanned English books and documents. This is a prerequisite for use and is for reference.

1. As a reader, page turning should be smooth, and it is best not to require loading time and font rendering time. At this point, almost all foreign PDF readers fail because, more or less, they all have visible font rendering time.

Foreign readers with shorter rendering times include: mantano and ezpdf. Repligo rendering is rough rendering first and then fine rendering. If you don't have obsessive-compulsive disorder in this regard, please ignore it.

2. I need the reader to support the colordict interface for word extraction. At this point, Adobe and Zhiqi Reading are completely defeated. In fact, I have used ezpdf, mantano, Zhiqi and Jingdu Tianxia have this function (although you can choose the dictionary fora, but this dictionary has too few dictionaries). Duokan only supports Kingsoft PowerWord. In the long run, I don’t think Duokan will support other dictionaries.

3. It should be convenient to click to retrieve words. In this regard, only ezpdf, Zhiqi and Jingdu Tianxia meet the requirements.

(Mantano’s anti-human word selection is completely rubbish: when picking words on nexus7, one letter will be fixed and a single word cannot be automatically picked according to spaces and punctuation marks. The first word must be selected. and the last letter. repligo can extract words but does not support colordict. Intelligent Device has been updated at the end of 2012 to support word extraction).

4. Page turning smoothness. This point is almost all qualified, not to mention that some people like to turn pages left and right. In this case, it is difficult to see the smoothness of page turning (this item varies from machine to machine and is for reference only).

The really smooth ones include Zhiqi and Duokan, and the relatively smooth ones include mantano. repligo and ezpdf lag behind visually due to their slightly slower loading speed. Jingdu Tianxia failed in this project because the frame rate when turning pages was so low in my opinion that it directly caused me to question the smoothness of the Android system.

5. Library management. I have no requirements for it, as long as it looks good, and this project is quite personal. So no comment. It is worth mentioning that mantano has powerful library management functions.

6. Trim the edges.

I don’t use this feature very often, so I’ll skip it. I have always used ezpdf to manually trim the edges. It is more accurate and can also choose to cut odd and even pages. Mantano also began to support manual edge trimming in an update in 2013. Recently, you can also manually trim edges and distinguish odd and even pages.

6. Set the complexity and customizability. To some extent the two are mutually exclusive, and I personally prefer the simple setup. Because I think that as a reading software, PDF reader should have a lower learning cost, that is, it should be faster to get started. But being too simple can easily lead to poor customization.

I think the representatives of complex settings are: ezpdf. I spent half a day getting familiar with its settings and had to go online to re-download the Chinese version. Even the Chinese version took me 2 hours to explore. Representatives of simple settings include: smart device reading.

It is so simple that I think there is no customization at all, and the background color cannot be set. Personally, I think the balance between the two is Jingdu Tianxia and mantano. Viewing more customizable content is considered a sufficient level.

7. Rearranged version. This function is never used, but it can be used to re-format the scanned PDF. I tried it, and there were not many errors, but the loading was slow.

8. Notes. At the end of the answer, I found that notes were not mentioned at all. I personally don’t use this feature often (many reader annotations are not saved in PDF files, which can cause trouble), but ezpdf’s complete note-taking feature still left a deep impression on me. It is very good to synchronize annotations with ezpdf in sync disk.