The projects in this category vary more than their feature lists suggest, and the variation that matters is not about features at all. Six checks take an hour in total and they predict the three year outcome better than any trial of the editor, because what fails is almost never the writing surface.
Check the license, then check what it asks of you
Confirm the license is one the Open Source Initiative recognizes rather than a source-available license that merely looks like one, because the second kind can change the terms of a commercial deployment later. For an internal base you are usually not redistributing anything, which makes most of the copyleft argument academic, but the distinction between open source and visible source is not academic at all. The practical test is whether the license text itself sets conditions on who may deploy it or at what scale. If it does, you are looking at a commercial license with the source included, which can be an entirely reasonable purchase and is not the thing you set out to evaluate.
Check the release cadence, not the star count
Look at how often releases ship and whether security fixes get their own release rather than waiting for the next feature drop. A project with occasional large releases is a project where you will be exposed between them, and popularity tells you nothing about this. Read the last year of releases rather than the last month. A project that shipped steadily and then went quiet is more worrying than one that never shipped fast, because the quiet usually means the maintainer's circumstances changed and nobody replaced them.
Check what search it actually ships
Some projects include a full text index that is genuinely adequate for a few hundred articles; others expect you to run a separate search service and wire it in. That is a second system to host, patch and back up, and it belongs in the decision rather than in a surprise during the install.
Check whether an article can have an owner and a review date
Most wiki-descended projects cannot express either, and the workaround is a convention that dies with the person enforcing it. If the fields are not there, decide now how you will track ownership outside the product, because discovering it later means retro-fitting it across everything already written. Where the fields are missing, the least bad workaround is a convention encoded in the article itself, an owner line and a checked-on line at the top of every page, plus a scheduled report that lists the overdue ones. It is uglier than a feature and it survives, which the informal version does not.
Check the upgrade path in the docs, before installing
Read the upgrade instructions for the last major version. If they are long, involve a database migration you would have to supervise, or contain the phrase about backing up first in bold, that is the task your team will be deferring. It is better to know its shape before there is content to lose.
Check the export by using it
Write ten articles, export them, and read what comes out. Clean files with titles and structure intact mean you can leave. A database dump means the content is hostage to the software, which is the outcome open source was supposed to prevent.
Questions people ask about open source knowledge management system
Is a wiki engine good enough?
For contribution, often better than a purpose-built base. For governance, weaker, because ownership and review are conventions rather than features. Engineering-heavy companies do well with one; most others struggle to keep it true.
What does it really cost?
A host, backups with a tested restore, the patch cycle, and the search service if the project needs one. No license fee, and a standing claim on somebody's week that belongs in the comparison.
Can we start here and move to a hosted product later?
Yes, if you verified the export first. That single check is the difference between a weekend and a project.
Is source-available the same as open source?
No. You can read the code and the terms can restrict how you deploy it or change on a later version. Read the actual license rather than the marketing page that describes it.
How many articles before self hosting stops being casual?
It is not the article count, it is the moment somebody outside the team depends on the base being up. From then on it needs monitoring and an owner like any other service.
Does open source help if our content cannot leave our infrastructure?
It is one of the two answers, the other being a vendor who will deploy into your environment. If the constraint is real and written into a contract, it narrows the field usefully rather than deciding it.