single point of failure

From IndieWeb
(Redirected from SPOF)

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; on the web, the most visible examples are silos and massive site outages when they all depend on a common provider like AWS.

SPOFs are an important thing to take into account when designing software, or creating a protocol, or setting up a personal websites.

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

Previous IndieWeb Examples

Service Examples


Main article: AWS Downtime



Silo Examples

Literally all the silos — when their site goes down, all your stuff there is inaccessible.

Single external authentication providers

  • Websites that only offer Twitter (or another silo) as an authentication provider will fail 100% of time to allow users access if Twitter (or that other silo) is down.


  • All users on a hosted instance of Mastodon or Diaspora will lose all services if that instance goes down

More Examples

  • 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