GNU Flymake

Flymake is a universal on-the-fly syntax checker for Emacs. When enabled, Flymake contacts one or more source backends to collect information about problems in the buffer, called diagnostics, and visually annotates them with a special face. The mode line displays overall status including totals for different types of diagnostics.

To learn about using Flymake, see Using Flymake.

When the Emacs LSP support mode Eglot is enabled, Flymake will use that as an additional back-end. See Eglot Features in Eglot: The Emacs LSP Client Flymake is also designed to be easily extended to support new backends via an Elisp interface. See Extending Flymake.

Historically, Flymake used to accept diagnostics from a single backend. Although obsolete, it is still functional. To learn how to use and customize it, see The legacy “Proc” backend.

This manual is for GNU Flymake (version 1.2.2, November 2021).

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