How to pitch a software idea to a potential employer?

I, as a software engineer, got contacter by a company to interview with them. I got the first "get to know each other + coding test" stage easily. During the itw, I realized they are making a sofware that is in the same vein as one of my hobby project. Their software is B2B, mine would be (it's not written yet) B2C. So, long story short, have some of you successfully pitched a software idea to a new company ? If so, how did you do ? Do you get some percentage off the sales of this software ?
Also, how do you prepare to pitch a software that doesn't exist yet ? Do you write SRS documents or is it too soon ?

Managers and employers : how would you feel if someone you are interviewing, is trying to pitch for a new idea, or a new software that you could do with him ?

I'm not sure I should talk to them about this idea of mine. They are B2B, this idea is B2C.. What are the chances they make this idea real without me ?

Thanks for your answers!

I'm not saying it can't happen but in general it doesn't happen the way you hope it will.

At this point in time you have nothing but a vague idea (all software ideas are vague before they get turned into code).

The company is willing to pay you money for your services which implies that they already have more ideas that they are capable of implementing at this moment.

Ideas are worthless in the sense that we don't know how to put a price on them.

You probably noticed that there is a marketplace for selling eggs or mortgage-based securities but there is no market for selling and buying ideas.

Why? Because before an idea is turned into a product, we don't know how valuable it'll be. Facebook made billions but none of its early competitors did (and there were a few).

So that is your first problem: putting a price on an idea is extremely tough.

Your second problem is that people who run the company probably think that they know what they are doing and won't be very receptive to an outsider telling them what to do.

Your third problem is that given that they are already doing very similar idea, chances are that they've already thought of your ideas and rejected them or they wanted to do them but don't have resources to implement everything and had to focus on a subset of the problem.

Problem number four: even if management of the company hasn't thought of those ideas and is receptive to your ideas, chances are that there's already a person in the company whose job is it to come up with ideas (product/program manager) and that person will be threaten by you and will do everything he can to torpedo you.

Finally, unless you have a patent, it's pretty much impossible to protect ideas. They'll either refuse to listen to your ideas before you become an employee (at which point they'll have the right to all your work-related ideas) or will listen to your ideas and pay someone to do them (which will cost them less than a cut of profits you hope for).

In conclusion: the deals like the one you imagine are unheard of.

In real world, if you want a cut of profits, you need to become a part owner of the business which means that you either started that business or were granted a very generous stock options.

If you want the job, your project cuts two ways, and you have to be careful how you come across.

Positively, having prior subject matter expertise should be a bonus - something that ought to let you hit the floor running faster than another comparable engineer.

Negatively, your project creates a potential conflict of interest. Pitching it, in my view at least, makes it look as though as an employee, that conflict is going to come to the fore.

So if you want the job, you may want to frame it in the first way, and be prepared to shelve the project if that's necessary.

If you get the job, you may have other opportunities down the line - and you'll learn that from the inside.

And if you don't, you have a potential fallback position - use the contacts to work out who might be interested in a pitch of the project for partnership or investment.