single point of failure

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Single points of failure (SPOFs) are aspects or parts of a system which, when they fail, cause crucial parts of (or the entire) system to fail. SPOFs are an important thing to take into account when designing software or creating a protocol.

IndieWeb Examples

Examples of IndieWeb singular services/sites that are heavily relied upon by the community, what functions they’re used for, and code you might find on your site if you’re depending on them:

Bridgy (running Bridgy)

  • Receiving (and sometimes displaying) responses
  • <link rel="webmention" href=""/>

Alternatives to

  • OpenID delegation
    • <link rel="openid.server" href=""/>
  • IndieAuth authorization_endpoint
    • <link rel="authorization_endpoint" href=""/>
  • IndieAuth token_endpoint
    • <link rel="token_endpoint" href=""/>

Alternatives to

Aperture (running Aperture)

  • Microsub server, subscriptions, caching feeds
    • <link rel="microsub" href=""/>

Alternatives to Aperture

Superfeedr service of Superfeedr

  • WebSub notification delegation
    • <link rel="hub" href=""/>

Alternatives to Superfeedr

More Examples

  • silos
  • Websites that only offer Twitter as authentication provider will fail 100% of time to allow users access if Twitter is down
  • All the downtime of services which depend on AWS when it goes down
  • All users on a hosted instance of Mastodon or Diaspora will lose all services if that instance goes down
  • Websites on hosting providers, DNS providers or the like that go down will lose access to the Web.


  • 2021-03-27 Bloomberg: Suez Shows Civilization Is More Vulnerable Than We Think

    [...] In the strategy and military realm, such bottlenecks are also known as “choke points.” And we often don’t pay enough attention to them until something goes wrong.

    Systems designers strive to avoid these single points of failure, so that transport, energy and communication networks are able to withstand attacks or unexpected calamities. [...]

    [Emphasis added]

See Also