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.

Many customization options from the built-in ispell library are also relevant, notably ispell-program-name. Hunspell and Aspell are the most common choices. Aspell is faster, but in my experience Hunspell has better correction suggestions and is sufficiently performant.

Type M-x jit-spell-change-dictionary RET to choose a different spelling language. If you use Hunspell, you will be able to select multiple languages. Other spellchecking programs are limited to a single language.

The default spellchecking language is determined from your system settings. To change that, customize the variable ispell-dictionary. To change the spellchecking language of a specific file, type M-x add-file-local-variable RET ispell-local-dictionary RET followed by the desired language (remember to enclose it in quotation marks, since that variable must be a string). Similarly, you can use directory-local variables to adjust the spellchecking language for collections of files.

When using Hunspell, you can set those variables to a comma-separated list of dictionaries for multi-language spellchecking. See the explanation of the -d switch in Hunspell's man page for more information.

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.

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