How does WordPress know a plugin has an available update?

Is the process handled by the readme.txt file? I am trying to manage 3rd party plugins that I alter in an effort to better fit/meet the needs of my instance of WordPress but I would like to maintain the functionality that alerts the CMS user that an update is available for the 3rd party plugin.

If I alter a plugin’s title will WordPress still know if there is an update to that plugin's code base? E.g. ‘Plugin Name’ (changed to) ‘Plugin Name – Modified’

1 Answer 1


Basically it sends a list of your plugins to the wordpress.org API server, which does some black magic to try to figure out if any of the plugins you have match the ones it has, then it returns version info back for them.

The API uses a rather elaborate mechanism to match plugins against plugins it knows about, but these are the main things checked for: Plugin URI, Plugin Name, and Plugin slug (the directory name the plugin is in)

Change any of those and you reduce the chances of it finding a match, but it might still get it if two of them match, for example.

Info in the readme.txt is not used for this. The header of the plugin's PHP file itself is used.

  • I'm somewhat surprised that there isn't some fixed, unique identifier - but, I suppose that would be impossible to manage. Commented Jul 19, 2011 at 19:08
  • It has been suggested before, but there hasn't really been a need for one. If one was to be created, then I suspect we'd use a GUID or something similar, but then you still run into the problem of malicious people duplicating somebody else's GUID in an attempt to "take over" a plugin or something. Or people simply copying a GUID through ignorance or laziness. It's not a solution, basically, because you still have to use fuzzy logic to detect this sort of thing.
    – Otto
    Commented Jul 19, 2011 at 19:19
  • 2
    Note that Plugin URI tends to be relatively unique, which is why it's the primary means of identification here. People putting in a plugin want to use their own URI that they control, so this tends to work very well for uniqueness purposes. It's also why there is a separate Author URI, to avoid people using the same URI for all their plugins for the linking benefit.
    – Otto
    Commented Jul 19, 2011 at 19:22

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