spdx.el provides SPDX license header and copyright insertion.

Please install spdx from melpa.

Put spdx.el in your Emacs system. Add the following to your .emacs:

(require 'spdx)
(define-key prog-mode-map (kbd "C-c i l") #'spdx-insert-spdx)

Or use use-package with straight.el:

(use-package spdx
  :ensure t
  :straight (:host github :repo "condy0919/spdx.el")
  :bind (:map prog-mode-map
         ("C-c i l" . spdx-insert-spdx))
  :custom
  (spdx-copyright-holder 'auto)
  (spdx-project-detection 'auto))

you can press C-c i l to trigger spdx-insert-spdx

Or manually run M-x spdx-insert-spdx

Then, spdx.el will ask you to select a license. It's done by completing-read.

After that, the license header will be written. An example follows.

;; SPDX-License-Identifier: MIT

If you use tempo, add spdx-tempo-setup to the mode specific hook. Type spdx then M-x tempo-expand-if-complete, you will get the same result as above.

It's recommanded to combine tempo-expand-if-complete with hippie-expand:

(use-package hippie-exp
  :ensure nil
  :bind ([remap dabbrev-expand] . hippie-expand)
  :config
  (defun try-expand-tempo (_old)
    (require 'tempo)
    (tempo-expand-if-complete))
  :custom
  (hippie-expand-try-functions-list '(try-expand-tempo
                                      try-expand-dabbrev
                                      try-expand-dabbrev-all-buffers
                                      try-expand-dabbrev-from-kill
                                      try-complete-file-name-partially
                                      try-complete-file-name
                                      try-expand-all-abbrevs
                                      try-expand-list
                                      try-expand-line
                                      try-complete-lisp-symbol-partially
                                      try-complete-lisp-symbol)))

Let M-/ rule the world.

• spdx-insert-spdx inserts a SPDX license header.
• spdx-insert-spdx-only inserts a SPDX license header without comments.
• spdx-insert-spdx-identifier-only inserts a SPDX identifier only.
• spdx-insert-copyright inserts a copyright header.
• spdx-insert-spdx-copyrightinserts a SPDX license and copyright header.

The following tempo snippets can be expanded via M-x tempo-expand-if-complete. Make sure spdx-tempo-setup is called to access these tempo snippets.

• spdx expands to a SPDX license header.
• spdxo expands to a SPDX license header without comments.
• spdxi expands to a SPDX identifier only.
• cpy expands to a copyright header.
• spdxcpy expands to a SPDX license and copyright header.

• spdx-copyright-holder ('auto by default)
• spdx-copyright-sign ('ascii by default)
• spdx-project-detection ('auto by default)
• spdx-ignore-deprecated (nil by default)

lice-el provides license template management and file header insertion.

The content of license is inserted while spdx.el only inserts two lines.

;; Copyright (C)  spdx.el Authors
;; SPDX-License-Identifier: MIT

If you use lice-el, you may also need to hide the massive headers. Take a look at the builtin elide-head package.

license-snippets is a license snippet collection of yasnippet.

spdx.el uses the builtin completion system tempo without dependencies of third party libraries.

license-template creates LICENSE file using GitHub API. It's NOT used to insert license header.

Emacs has a builtin copyright package providing copyright header insertion. However, the copyright elisp-mode has only one leading semicolon.

;Copyright (C) 2020 by Me

;; M-x copyright

spdx.el inserts with ;; with one space following.

;; Copyright (C) 2020  spdx.el Authors

;; M-x spdx-insert-copyright

If you found the spdx-spdx-identifiers is out of date, don't hesitate to raise a PR.

1. spdx-insert-spdx-copyright failed to work in text-mode.

   Now, it works. Even though text-mode hasn't defined comment syntax, spdx.el will ask user to define it.