Open source alternatives to forms.app

By GitHub stars it is HeyForm, with 9,074 stars and a commit on 12 Nov. Choose HeyForm when you want conversational forms with payments, logic and custom CSS whose source code you can change. Next come OpnForm (4,009 stars) and Palform (49 stars).

Yes. The code of all 3 is public under AGPL 3.0, so you can use them with no licence fee. Running one yourself costs the server and your time to look after it, and some makers also sell a hosted plan.

Start from the job you use forms.app for. Choose Palform when you need forms hosted in the EU with no tracking scripts on the fill page and code you can audit. Choose OpnForm when you want forms whose AGPL-3.0 code you can audit and host, with webhooks and an API on every plan.

2 of the 3: HeyForm and OpnForm. Each tool's page says what it needs to run.

All 3 we track had a commit in the last 30 days, among them HeyForm, OpnForm and Palform. A recent commit shows the project is kept up, not that it will stay that way.

AGPL 3.0 (3). GPL and AGPL ask you to share your changes under the same licence when you give the software to others, and AGPL also counts letting people use it over a network.

The hosting. forms.app's maker runs the servers for you; with an open source tool the updates, backups, security fixes and support are yours, unless you take the maker's hosted plan. Features differ too, so check what each one imports and exports before you move your data.