texapi – Macros to write format-independent packages

Texapi pro­vides util­ity macros to write for­mat-in­de­pen­dent (and -aware) pack­ages. It is sim­i­lar in spirit to the etool­box, ex­cept that it isn’t tied to LaTeX.
Tools in­clude: en­gine and for­mat de­tec­tion, ex­pan­sion con­trol, com­mand def­i­ni­tion and ma­nip­u­la­tion, var­i­ous test­ing macros, string op­er­a­tions, and highly cus­tomiz­able while and for loops.
The pack­age re­quires e-TeX (and, should you want to com­pile its doc­u­men­ta­tion, the pi­tex pack­age is also needed).