Founder = worked on biz for months or years without salary. (If founders did have salaries then that’s a different situation.) If you get to join an existing startup with a salary then you’re basically post-founder stage, as the company already raised capital. Of course, that doesn’t mean you couldn’t get the title but your equity is likely going to be lower regardless.

Founding engineer = first engineer but it’s not clear yet what the long term role should be (eg CTO vs VP Eng). Sometimes it means the person is very junior and it’s a wait and see type of situation. Sometimes it means it’s not clear to the involved sheet things will head in terms of your work.

At least that’s how I’ve been using them. If you joined my startup as a first engineer, then you can pick your title, but I would nudge you in the direction that makes sense. It often comes down to many CTO folks being architects and not active code writers. In an early startup that’s not always ideal of course, why it’s often better to start with a founding engineer title.

If you think you’re heading in the direction of being the future CTO, I think you should angle for 5%. My guess is they’re not seeing you as that (eg if you’re very junior), but your equity is def very strong for a non-CTO role IMHO.

P.S.: the company valuation and your market comp determine your %. For example, if your market value is considered $200k and the company can afford to pay only a $100k salary then you’d get $100k worth of equity.