GNU ELPA: jit-spell

To enable spell checking in a buffer, type M-x jit-spell-mode RET. To correct a misspelling, you can right-click the word (assuming you have context-menu-mode activated) or call the command jit-spell-correct-word, which uses the minibuffer to read a correction or accept the word.

To make your settings permanent, you may wish to add some variant of the following to your init file:

(add-hook 'text-mode-hook 'jit-spell-mode)
(add-hook 'prog-mode-hook 'jit-spell-mode)
(with-eval-after-load 'jit-spell
  (keymap-set jit-spell-mode-map "C-;" 'jit-spell-correct-word))

Try also M-x customize-group RET jit-spell RET to see a listing of all possible customization options.

Type M-x jit-spell-dictionary RET to choose a different spelling language (or languages). You also call that command with a prefix argument in order to save the dictionary choice permanently, either as a file-local variable or dir-local variable.

Moreover, you can set the default dictionary by customizing the variable jit-spell-dictionary. If it is nil, the default dictionary is determined by the “legacy” ispell-dictionary variable or your system's locale setting.

Often there are regions of the buffer that should be ignored for spell-checking purposes. In most cases, no additional configuration is necessary.

The simplest mechanism to make adjustments is the user option jit-spell-ignored-faces. Any word fontified with one of these faces in this list ignored by jit-spell. To find out which faces are present on a given character, you can use the describe-char command.

In all programming language modes, spell checking is restricted to comments, docstrings and strings. This can be modified by customizing the variable jit-spell-prog-mode-faces.

jit-spell supports two spellchecking backends. The default method is to run a spellchecker as a subprocess, using the standard ispell -a interface. This forces us to compute all correction suggestions for misspellings eagerly, even if they will never be used. As a consequence, it takes (visibly) longer to complete and uses more systems resources. That said, since jit-spell runs asynchronously, it should not slow down Emacs itself.

As a better performing alternative, jit-spell can use vibe-spell, a port of Hunspell to pure Emacs Lisp. It is selected automatically as the jit-spell backend when available, so it suffices to install that package with the following command:

M-x package-vc-install RET https://github.com/astoff/vibe-spell RET

Discussions, suggestions and code contributions are welcome! Since this package is part of GNU ELPA, contributions require a copyright assignment to the FSF.