The Review Board diff viewer is one of the best on the market. It has many ways to help

you look through a change and focus on what's important.
Here's just a few of the features we provide:



Detailed file index
The file index lists all the files modified in the diff, along with a graph showing the

  relative number of inserts, deletes, and replaces.
The thickness of the ring shows how much of the file is modified (and will be a full red

  or green circle, if the file is deleted or added).
The colored dots on the side link to the matching changed chunks for that file.





Multi-line commenting
Click a line number, or click and drag down several lines to comment on those lines.





Syntax highlighting
Every diff is syntax-highlighted, making it easier to see, for instance, what's a string

  and what's a reserved keyword.
This supports highlighting file formats of all kinds.





Collapsable diffs
Diffs are shown collapsed, only showing what changed and the immediate lines around it.
A header is shown above each change, showing the nearest function or class. Clicking on the

  header will show all unchangedl ines up to that function or class.
Alternatively, click the [+] 20 to show 20 more lines, or the [+] to show all the lines

  hidden behind that header.





Moved code detection
Significant code changes that move around a file are specially shown with little move flags

  saying where they went to or where they came from. You can rely on these to know that you

  don't need to give that code another look.
For example, see how the __init__ function was moved in /r/2/diff/





Interdiffs
When reviewing multiple iterations of a change, you can view an "interdiff," the diff

  between two diffs. It's easy to see what has actually changed. For example, see /r/2/diff/1-2/





Indentation change indicators
When code is indented or un-indented, we show it cleanly without showing a full line change.

  These are shown by >>>> and <<<< markers on lines, which you can see in /r/2/diff/ and in

  /r/2/diff/1-2/
Unlike most diff viewers, you won't have to waste your time examining every line that was

  indented, looking for changes.
This will even differentiate between spaces and tabs. If someone accidentally indents

  the wrong way, you'll know.





See changes made within a line
When replacing just part of a line, we highlight the changes, making it much easier to see

  the addition of a word, renaming of a variable, or even the accidental removal of a semicolon.





Download any file in the diff
Simply click the little down arrow next to the "Revision" or "New Change" in the diff's

  header to download the full content of either the file on the left-hand side or right-hand

  side.


Click View Diff in the top-right to look at the diff for this review request

to play around with the diffs.