Green’s Dictionary of Slang

1. a tale-teller, one who talks ‘out of turn’.

c.1468		‘Trial of Joseph and Mary’ Coventry Mysteries (1841) 131: Kytt Cakelere and Colett Crane.
1598		in Florio Worlde of Wordes n.p.: Gracchione, a chatter, a cackler, a railer, a prater, a tatler.
1723		‘Whipping-Tom’ Democritus III 6: Entring [...] Oliver’s Tabernacle, situated not a Mile from the Gate-house, I hear’d a fanatical Cackler.
1737, 1759, 1760, 1776		in Bailey Universal Etym. Eng. Dict.
1834		‘Jack Downing’ Andrew Jackson 119: The gineral tu, had his cacklers.
1850		E.V. Kenealy Goethe: a New Pantomime in Poetical Works 2 (1878) 334: Antic, Blusterer, Cackler, Toper, / Won't you let the sex alone.
1859		Glasgow Sentinel 17 Sept. 4/4: An age when pulpits and platforms are crowded with political and religious cacklers.
1866		Sportsman 25 Sept. 2/1: Notes on News [...] Laughter out place seems peculiarly English [...] one might pretty fairly assume the unseemly cackler to be the biggest fool in court.
1878		Browning Poetical Works (1899) 97: If they dared Count you a cackler – wonders never cease!

2. (US) an office worker, a clerk [note Irwin (1931): Cackler. – [...] A white collar worker; this name originated by the I.W.W., who have had a hard time interesting this class of worker in their movement, and who say a clerk or office worker will talk, ‘cackle,’ all day and do nothing to improve his condition].

1926		N. Klein ‘Hobo Lingo’ in AS I:12 650: Cacklers — white collared office workers.
1930		‘Dean Stiff’ Milk and Honey Route 201: Cacklers – White collar workers.
1949		Monteleone Criminal Sl. (rev. edn) 41: cackler A prison clerk.
1960, 1975		(ref. to 1920s) Wentworth & Flexner DAS.