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String Substitution

The String Substitution module lets a user replace one typed sequence of characters with another. If a string of characters you type matches an entry in your dictionary, it gets deleted and replaced with the corresponding replacement string.

Potential uses:

  • Rudimentary auto-correct: replace yuo with you
  • Text expansion, à la espanso: when :sig is typed, replace it with John Doe, or turn idk into I don't know


The String Substitution module takes a single argument to be passed during initialization: a user-defined dictionary where the keys are the text to be replaced and the values are the replacement text.

Example is as follows:

from kmk.modules.string_substitution import StringSubstitution

my_dictionary = {
'yuo': 'you',
':sig': 'John Doe',
'idk': "I don't know"
string_substitution = StringSubstitution(dictionary=my_dictionary)


  1. Consider prefixing text expansion entries with a symbol to prevent accidental activations: :sig, !email, etc.
  2. If you want multiple similar replacements, consider adding a number to prevent unreachable matches: replaceme1, replaceme2, etc.


  1. Currently supports characters for which there is a corresponding keycode in KMK - support for international characters is not implemented.
  2. Since this runs on your keyboard, it is not context-aware. It can't tell if you are typing in a valid text field or not.
  3. In the interest of a responsive typing experience, the first valid match will be used as soon as it is found. If your dictionary contains "abc" and "abcd", "abcd" will not be matchable.