Is it a good practice to provide open-source version of your paid app?

I think it will not harm. Usually, because people who cannot pay - will not. People/companies who need high quality products and/or have expensive labour will choose a paid plan.

For Example, Elasticsearch. So popular, fully open-sourced. Still, Elastic sells fully managed clusters. And, many companies choose Enterprise license.

If you want smaller example. 2 month prior the beta launch of NewsCatcherAPI (https://newscatcherapi.com) I decided to open source some code we've done (https://github.com/kotartemiy/newscatcher). We ended up having 300 people fro beta sign-up. Then, 700 pre-launch.

So, I attracted lots of developers who already liked the field via open-sourcing

Edit: grammar

It will substantially harm sales of B2C products, but it may make sense for B2B products that require support and training and aren't based on any substantial know how/trade secrets. In that case releasing as open source might even be beneficial. A good trade off is to release libraries as open source but keep parts of your final product (e.g. GUI) proprietary.

Even in the B2B market successful open source companies often use dual licenses and release the open source version as a sort of crippleware by keeping essential libraries and tools proprietary or under very restrictive open source licenses.

If I would ever would launch a product, I would choose AGPL for the open source side and provide a commercial license for those who need it. This has the advantage over MIT/Apache that if someone wants to build a business arround your free software, they have to provide their changes to everyone.

I discovered this for pgmodeler[1] and found it a very good way to monetize the development of the application.

[1] https://github.com/pgmodeler/pgmodeler

If you want to open all of your product's code, then you might want to use a public-private licensing model. https://indieopensource.com/public-private/users

Have a look at the Parity Public License and the Prosperity Public License. https://paritylicense.com/ https://prosperitylicense.com/

Those two licenses allow others to read, modify and redistribute your code. Parity requires that users open source their code, while Prosperity only allows non-commercial usage. If a potential customer doesn't want to be restricted by the public license you choose, they can instead buy a private license.

Also see License Zero's private license. https://licensezero.com/licenses/private

It shouldn't if you model it right. A lot of companies do very well with 'open core', which is sort of this. I think there's other successful ones as well.

For instance laravel has a hosted invoicing app: InvoiceNinja, but it's open source too, as in you can host it yourself, just it doesn't have any of the multi-tenant stuff baked in.

You might check out Aseprite. It's a a software which binaries are paid, but source code is free and you can just conpile a program for free if you want.

Well, I've been a user of a couple closed-source apps that have apparently fallen by the wayside and don't get any development anymore. Meanwhile, the open-source ecosystem doesn't have good native alternatives specifically in those areas.

So personally I'd like it if authors at least made provisions for open-sourcing their apps in their will, or in the ‘life moved on’ plan.

If you wanted me to use and pay for your software, you'd need to provide the source. I have no problem paying for software - in fact when the price is fair I do so liberally.

However, if a copy of the source doesn't come with my purchase then I am much, much less likely to buy it. I'm obviously only one user, so take my anecdote with a grain of salt.

I use a model of "source-included" personally. This way I respect (most of) the freedom of my users, but not at my own expense.

I don't have a vetted license in mind tho. So far I haven't needed it. Someday hopefully I will ;-)

Side note: make sure you have build instructions for your users tho. I don't like when I buy software that is source included but then building is impossible because `make && make install` (or whatever for that platform) doesn't work and there aren't any instructions. You don't want your buyers to have remorse.

*Other side note: Thanks for thinking about this! It's really cool of you to think about community

In a word: Depends. Microsoft for instance nailed it perfectly. For many years billions of devices ran cracked Windows copies and truthfully that didn't bother individual users in most countries. While illegal, realistically no one was going to bother with 15 year old Jimmy somewhere in the countryside. But they kept insisting on it. Until they figured out that locking and blocking was never going to work. So they adopted the WinRAR approach: "Hey you are running an unregistered version past your trial. This may have legal consequences."

But the thing is that while Windows has many alternatives (I'm saying this as someone who's been using Linux full time since the age of 11), for most people that really isn't an option: while you can get things like Photoshop to run on Linux, the experience is anything but optimal. I don't use Photoshop at all(or any graphics programs). But say my mum who's an artist - she practically has to use Windows. So in that sense, Microsoft has no benefit in open-sourcing anything, even though they have been doing that in recent years. I remember seeing a huge discussion on Twitter last year and several people said that at some point Microsoft will become a completely open-source company. Personally I doubt it, but who knows...

Now let's look at another example - Google, and Chrome in particular. As a browser, Chrome has a million and one alternatives, many of which are very good. So having an open source alternative is in their best interest - think of how many browsers [1] use and contribute to the chromium engine - it's a win-win situation for everyone: Big community, a thousand eyes looking into it's internals(and undeniably catching security flaws).

Then again, this isn't always applicable. Even more so with javascript and npm in particular, which has turned everything into an endless rabbit hole of packages, dependencies and before-after install scripts.

[1] https://en.wikipedia.org/wiki/Chromium_(web_browser)#Active

If your marketplace is for “open core” licensed code it would make sense for you to use that model too.

It may not harm you on the sales side of things directly, but going open source will make it easy for your competition to catch up, which might matter if you find traction with your product.

If you care about the liberty of your users and ethics, you should release the all code as free software. Information is not property.

You can create your business around service providing rather than using state legislation to coerce people to not reproduce and alter information they know.