Full conjugations of nearly all French verbs in one page

Like columns attract:  If we arrange the columns of the table of French verb inflections in the order Infinitive, Future, Present indicative, Present subjunctive, Imperfect indicative, Past simple, Imperfect subjunctive,  and hang the participles under the columns for their respective tenses,  we place similar forms close together and thereby emphasize the repeated strings (which may be further highlighted by text markup).  In a table thus arranged, I use the symbols 1, 2, 3, 3a, 4, 4a  to denote the stems of six principal parts (PPs), and show how these stems normally propagate to other parts, taking on various endings. The chosen PPs are respectively the infinitive, 1st singular, 1st plural (3rd plural), past simple (past participle),  where the listed person & number are for the present indicative, "past simple" is for 1st singular, and a form in parentheses (corresponding to a stem number with suffix ‘a’) can be omitted from lists if it has the same stem as its predecessor. Thus the table, together with the simple rules for forming the imperative and conditional, predicts the inflections of any "regular" or "irregular" French verb with at most these six independent PPs: any verb covered by the table can be fully characterized by listing at most six PPs, and perhaps as few as four.  In "regular" verbs, and in many others that are not usually called regular, some of these four merge.

Stems of convenience:  If the e in -er verbs and the i in -ir verbs are considered to be included in the infinitive stems, the formation of the regular future stem is reduced to a single rule covering -er, -ir, -re, and -oir verbs. Although the past participle is usually considered more fundamental than the past simple, listing the latter first (and the former only if necessary) is conducive to brevity and uniformity.

Mixed conjugations:  Some -ire verbs behave almost like agir. Conversely, some -ir verbs and verb-groups are most easily described by saying that they form some stems as if  the infinitive ended in -er or -re or -ire instead of -ir.

Optional extras:  In the above six-PP scheme, the two parenthesized parts are optional in the sense that they are needed only if they have distinct stems. By introducing an optional future in square brackets, we can show the few cases in which the future stem departs from the infinitive. More rarely, we can follow parts 3 and 3a with [1st plural present subjunctive (3rd plural present subjunctive)], where the latter (with parentheses) is needed only if its stem differs from the former. Any subjunctive stems that double as imperative stems can be marked by asterisks; and if one of these stems also doubles as the present participle stem, this can be marked by a dagger. Thus we can describe all the inflections of nearly all French verbs with one table, a bunch of punctuated lists of PPs, and a handful of exceptional notes, and cram it all into one page (see the PDF).

Disclaimer:  I produced this page because I needed it — not because I didn't need it!

Acknowledgments:  My choice of principal parts is influenced by, but different from, the five-principal-part scheme of  H.W. Church, "Teaching the French verb", The Modern Language Journal, 5(5):249–55 (Feb. 1921), jstor.org/stable/313496, and the four-principal-part scheme of  E.P. Cleveland, "French verbs in a nutshell", The Virginia Teacher, 10(6):181–6 (June 1929). At this writing, I have not seen pp. 184–5 of the latter article, but the rest of it was a useful source of rules.  Some behaviors that I have treated as variant or irregular are explained by further rules given in  E. Escher, "French Verb-Tables: A Critical Discussion III", The Modern Language Journal, 8(2):93–102 (Nov. 1923), jstor.org/stable/314308, or  M.H. Duncan, "The French Verb: Aids toward Mastery", The French Review, 25(1):31–6 (Oct. 1951), jstor.org/stable/382968.