Did you test the behavior with the Google engine because if I remember well we already fetch the spellchecker of Google and show it as a suggestion?

Ohi! Thanks for the contribution. It is a useful and highly requested feature, however the implementation has some flaws. First, it doesn't support properly multiple languages currently, second it introduces a new dependency, what we try to avoid if it isn't necessary. I'm thinking about implementing it as a stand-alone plugin. In this case the extra dependency wouldn't cause an issue for all of our admins, anyone can decide if they want to install it. What do you think? If you agree, you can find an example stand-alone plugin here:https://github.com/asciimoo/searx_external_plugin_example