The Crossref Curriculum

Building URLs for DOIs containing special characters

You might see (or inherit responsibility for) older DOIs which contain other characters, and require special treatment in a URL:

  • Encode hash or pound sign # as %23
  • Encode left bracket ( or less than < as $lt; and right bracket ) or greater than > as &gt;
  • Do not encode forward slash /

For example, use:

https://doi.org/10.1002/(SICI)1521-3951(199911)216:1<135::AID-PSSB135>3.0.CO;2-%23

instead of:

https://doi.org/10.1002/(SICI)1521-3951(199911)216:1<135::AID-PSSB135>3.0.CO;2-#

Last Updated: 2020 April 8 by Laura J. Wilkinson