Do I Have the Freedom to Use and Modify the Open Source Code?

Short answer: almost always, yes. Longer answer: it depends on which license the project ships under, and that detail is worth actually reading before you build a business around it.

Permissive licenses, like MIT or Apache 2.0, give you very wide latitude. You can use, modify, and even fold the code into a proprietary product without being required to release your own changes. Copyleft licenses, like the GPL family, are more particular: if you distribute a modified version, you're generally required to share those modifications under the same license.

Neither type is "better," they just serve different goals. A permissive license favors adoption and commercial flexibility. A copyleft license favors keeping improvements flowing back into the shared codebase. What matters is picking tools whose license actually matches what you intend to build, rather than finding out after the fact that your use case wasn't covered.

That's usually the part we spend the most time on with a new client: not whether open source fits, but which specific license terms fit the way they plan to use, modify, and eventually distribute their software.