No need to reinvent the wheel → implement LanguageTool, which is open source (if not mistaken) and very powerful.

Spell checker is baked in in the Proton Desktop app under Edit > Check spelling while typing. But it's far from perfect.

I'd consider changing away from PMail

I agree, I want to convert fully to Proton platforms, but MANY features are missing; spell check, auto signature, are a couple that come to mind quickly.

This is pretty critical

you acknowledge receipt of my email suggesting a spelling checker, but yoiu make no reference to my question. Very poor from your side; it brings me closer to say farewell to your entire Proton mail and all that is associated to that.
Robert Jans

you, Proton, acknowledge receipt of my cry for a spelling checker, but that's all. I see no action or ant refernce to it.

Your continued silence brings me closer to fonally close my entire account with you guys..

Bye, bye.

When will a Spell checker be available? Most, if not all, email programs have spell checkers.

Unfortunately, there is no Mac version of TinySpell. I looked, and looked again.

TinySpelldotcom

Tiny Spell is a super lightweight, free and low cost option. No malware 100% CLEAN by Softpedia. Works on all browsers and desktop applications. It's been around since 2011 as best I know. Fast install. Never had a problem. Easily create User Dictionaries. Many standard/expected features. Scads of independent reviews linked at the main site. S'all I can say about it.

TinySpell works a h3ll of a lot faster than whomever from Protonmail is supposed to be paying attention to this thread but has been not responding to is since Jan 3 2018 (over five years as I write this). Fully operational in Protonmail desktop.

I run Windows. Does it run on that other operating system? Friends tell me it does.

Introduce an auto-correct feature for emails

Grammarly doesn't seem to be operational either for Proton sites, so an alternative solution might be not to block (or make it compatible) this service.

I told my wife there was a Spell Check for her email but was flabbergasted that your otherwise excellent service does not feature this old tech simple service! You seem to ignore User complaints on this. Get on the ball Proton!

For non native English people, this is a great value add.

Spell check is necessary.

Please add a spell checker, it is a basic essential for a paid mail application..

I have an even better idea....why not have someone at ProtonMail give a single response to all the 712 votes (so far). That certainly would be appreciated. What good is it to ask us to tell you how to improve ProtonMail (as if you didn't know from the beginning), then just let the comments pile up over the years, and you never respong in any way? If you responded somewher else, please let us know where to find it? Almost feels like you'r ignoring all of us paying customers! See that? My keyboard didn't thype the "e" in "you're". Happens a lot, but I don't always catch the spelling mistakes.

It's not my brain....it's my keyboard! Yes, I agree, a spell checker is definitely needed, and should be expected, especially since this is a paid Email. Same for not having a search function in Proton Calendar.

Spell... ;(

where is the speel checker????