It is important to note that "completely free, open-source, forever" plugins for InDesign are rare. Developers invest significant time because InDesign's SDK (Software Development Kit) is complex. However, several developers offer fully functional free tiers, trial versions without time limits (with watermarks), or donation-ware.
Here are the top contenders for an InDesign math plugin free solution.
For those working strictly with tables (like annual reports or financial prospectuses), TableSum is superior to Calc. indesign math plugin free
EasyMath is a plugin built on the CEP (Common Extensibility Platform). The developers offer a "Freemium" model. The free version restricts you to basic operations (addition, subtraction, multiplication, division) but removes the need to write code.
If you search forums for "InDesign math plugin free," the overwhelming champion is a script simply called Calc.js. It is important to note that "completely free,
There’s a little-known open-source tool called Tex2Id (TeX to InDesign) – it’s not a plugin but a script. It’s free, but requires some setup:
Verdict: Powerful for power users, but overkill for most. The SVG method is simpler. Verdict: Powerful for power users, but overkill for most
MathMagic is a dedicated equation editor that has a plugin for InDesign. While the full "Pro" version is paid, they historically offered a Lite or Personal version for free (or very low cost).
Limitation: The free version does not auto-update. If you change a number in your layout, you must run the math again.
While waiting for your plugin, know that InDesign does have three hidden math superpowers: